Preheat oven to 350° F.
Purée tomatoes and onion in blender until smooth, about 15 seconds. Transfer mixture to liquid measuring cup; you should have 2 cups (if necessary spoon off excess so that the volume equals 2 cups, or add some water so that the volume equals 2 cups). Set aside.
Mix tomato paste with chicken broth. Set aside.
Place rice in large fine-mesh strainer and rinse under cold running water until water runs clear, about 1½ minutes. Shake rice vigorously in strainer to remove all excess water.
Heat oil in heavy-bottomed oven safe 12-inch skillet with a tight fitting lid over medium-high heat, 1 to 2 minutes. Drop 3 or 4 grains of rice in oil; if grains sizzle, oil is ready. Add rice and fry, stirring frequently, until rice is light golden and translucent, 6 to 8 minutes. Reduce heat to medium, add garlic and seeded minced jalapeños; cook, stirring constantly, until fragrant, about 1 ½ minutes. Stir in pureed tomatoes and onions, chicken broth, tomato paste, salt and pepper; increase heat to medium-high and bring to boil.
Cover pan with paper towel and lid and transfer to oven; bake until liquid is absorbed and rice is tender, 25 to 30 minutes, stirring well after 15 minutes. If necessary add additional liquid.
Yield: 6 to 8 servings.