Make-Ahead Vegetable Tian is as delicious to eat as it is beautiful to present. Imagine layered overlapping alternating potatoes, zucchini and tomatoes sitting atop luscious caramelized onions topped with Gruyère cheese. The vegetable tian is the perfect side dish to serve for a special occasion or anytime for that matter. What’s even better is that the leftovers, if any are just as amazing.

What is a Tian?

You may or may not have ever heard of a tian.

The name hails from Provence where a tian is an earthenware vessel that is used for both cooking and serving. A tian is also a dish with layers of alternating vegetables. Unlike ratatouille, the layers of vegetables are typically upright creating a stunning presentation.

Here’s a Quick Look at How to Make this Amazing Dish

Ingredients for Make-Ahead Vegetable Tian

Even though it might look complicated, the vegetable tian uses simple ingredients.

The Vegetables: While different vegetables can be used, my favorites are onions flavored with garlic, potatoes, zucchini and tomatoes. I try to use vegetables that are roughly the same size in diameter because of the way that they are layered. Therefore, I generally use Yukon Gold Potatoes because of their size and their cooked consistency. I try to find a large zucchini because of the size, and use Roma tomatoes because of their size.
Kosher Salt: As you may know, both zucchini and tomatoes have a lot water in them. Therefore, to avoid a soupy tian, I use Kosher salt to draw out excess moisture. I also use salt to flavor the onions and the potatoes.
The Spices: I like to use dried thyme, dried basil, dried oregano and black pepper to flavor the tian.
Olive Oil: I use olive oil to both cook the onions and as a drizzle on top of the tian.
The Cheese: My favorite cheese to use to top the vegetable tian is Gruyère. I’ve also used Monterey Jack, Parmesan and Mozzarella cheese.

The Experiment

I spent some time researching different recipes on the Internet for the vegetable tian. After a fair amount of experimentation, I was able to perfect this dish.

First, I cooked the onions longer that was suggested in some of the recipes. In the first half, I cooked the onions with salt, pepper and thyme in a covered skillet. Then cooked the onions the rest of the time uncovered.

Next, most of the recipes that I looked at didn’t cook the potatoes before layering them with the zucchini and tomatoes. The first time that I made this, I didn’t cook the potatoes either. The result, at least for me was that the potatoes were not sufficiently cooked in the final dish. Also, because I wanted to be able to make the vegetable tian ahead of time, I wanted to keep the potatoes from discoloring. Therefore, I cooked the potatoes before assembling the tian.

Another thing that I did differently was to follow Julia Child’s advice and salt the tomatoes and the zucchini ahead of time. The salt helps to draw out excess moisture and keeps the vegetable tian from being soupy. It also flavors the tomatoes and zucchini.

The Onions

I started by slicing the onions. Then, I heated some olive oil in a large skillet over medium heat and added the onions. I sprinkled on some salt, dried thyme and pepper and gave the onions a stir.

Next, I placed a paper towel on top of the skillet, covered the skillet with the lid and cooked the onions for 10 minutes. The reason for using the paper towel was to trap excess condensation as the onions cooked.

After 10 minutes, I removed the paper towel and lid, and continued cooking the onions for an additional 10 minutes until they started to caramelize. Finally, I added the minced garlic and cooked the mixture for about 30 seconds until the garlic was fragrant.

I removed the onions from the heat and transferred them to a 2 1/2 quart casserole dish.

The Rest of the Vegetables

To start with, I cut the potatoes, tomatoes and zucchini into 1/4-inch slices.

I boiled the potatoes in salted water for 8 minutes. After 8 minuteIs, I drained the potatoes and placed them in a single layer on a paper towel lined baking sheet to dry out (Photo 1).

While the potatoes were cooking, placed the tomatoes (Photo 2) and zucchini (Photo 3) in single layers on paper towel lined baking sheets. I sprinkled each with 1 teaspoon of Kosher salt and let them sit for 30 minutes. After 30 minutes, I blotted the tomatoes and zucchini with paper towels to remove as much moisture as possible.

Assembling the Vegetable Tian

At this point, the onions had been cooked and placed in the casserole dish. Also, the potatoes had been cooked and dried, and the tomatoes and zucchini had been salted and blotted dry. Therefore, it was time to assemble the vegetable tian.

Layer slices of tomato, potato and zucchini alternately on top of the onions, fitting the layers upright. I covered the onions completely with the layers.

Next, I drizzled the vegetables with 2 teaspoons of olive oil and sprinkle the vegetables with 1/4 teaspoon each of dried thyme, dried basil and dried oregano. I covered the dish with aluminum foil.

At this point, the vegetable tian could either be baked or be refrigerated for later baking. Because I wasn’t ready to bake it, I placed the casserole in the refrigerator.

Finishing the Vegetable Tian

I preheated the oven to 375°F. I baked the vegetable tian covered for 40 minutes. After 40 minutes, I removed it from the oven and removed the aluminum foil. I sprinkled the top with the shredded Gruyère cheese.

I returned the casserole uncovered to the 375°F oven for another 30 minutes. After the additional 30 minutes, the cheese was melted and the vegetables were perfectly cooked.

To say that the Make-Ahead Vegetable Tian was a masterpiece to look at and to taste is an understatement. It was absolutely delicious. In addition, the leftovers reheated beautifully. Yum!

Chula’s Expert Tips

The number of slices of zucchini, potato and tomato that you will need ultimately depends on the size of your casserole dish. My casserole dish was oval-shaped and 11 1/2 by 8-inches. For this particular dish, I needed 36 slices each of zucchini, potatoes and tomatoes.
Salt is an important ingredient in this recipe for three reasons. First, it seasons the onions as they cook. Second, it seasons the potatoes as they are boiling in salted water. Finally it removes excess liquid from the zucchini and tomatoes before they are cooked and also flavors the zucchini and tomatoes. Because both zucchini and tomatoes have a lot of water in them, the tian would be quite soupy if the excess liquid were not removed. The salting is a technique that Julia Child used. In the end, all of the vegetables were perfectly seasoned.
I like to use Gruyère cheese in this dish. However, you could also use Monterey Jack, Parmesan or Mozzarella cheese in place of the Gruyère cheese.
When I cook the onions, I like to place paper towels on the skillet before putting the lid on. The reason for this is that the paper towels trap the condensation that rises as the onions are cooking. This helps to remove excess moisture from the onions as they cook and aids in their caramelization.
If you are going to bake the tian as soon as it has been assembled, you can reduce the initial cooking time from 40 minutes to 35 minutes.
Leftovers, if any are amazing. I like to reheat them covered in the microwave for several minutes until heated through.

Other Awesome Vegetable Casseroles

Vegetable casseroles make delicious side dishes for a number of different entrées. Here are some of my favorite vegetable casserole recipes:

Easy Make-Ahead Zucchini Gratin: A gratin is a dish topped with a golden browned crust of breadcrumbs and/or melted cheese. In France, gratins are generally made with potatoes. This Easy Make Ahead Zucchini Gratin is an amazing deviation which will have you coming back for more!
Cheesy Southern Yellow Squash Casserole: Cheesy Southern Yellow Squash Casserole takes the lowly squash to new levels with this simple to make recipe. It doesn’t have any eggs, sour cream or mayonnaise often found in squash casseroles. Rather, it’s flavored with just onions, bacon and cheese.
Ratatouille à la Julia Child: Ratatouille à la Julia Child is an amazing dish. My inspiration for this dish was Julia Child’s recipe in The Way to Cook. I’ve been making this ratatouille for some time. As always, her recipe and approach never disappoint. It is the perfect vegetarian dish that is loaded with delicious ingredients that are cooked to perfection.
Cheesy Bacon Ranch Potatoes: Cheesy Bacon Ranch Potatoes are the ultimate in simplicity and taste making them the perfect side dish for any occasion. Once you try them, you’ll keep coming back for more.

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Make-Ahead Vegetable Tian