Step 1

Preheat the oven to 350 degrees F (175 degrees C). Place taco shells on a baking sheet.

Step 2

Heat oil in a large skillet over medium heat; stir in onion and garlic. Cook and stir until the onion has softened and turned translucent, about 5 minutes. Add chicken, tomato sauce, 3 tablespoons salsa, and taco seasoning; stir well. Cook until heated through, stirring occasionally, 5 to 6 minutes.

Step 3

Meanwhile, put refried beans in a microwave-safe container. Stir, cover, and microwave on high until hot, 3 to 5 minutes. Stir again and set aside.

Step 4

Warm taco shells in the preheated oven for 3 to 5 minutes.

Step 5

Place warmed taco shells on a serving platter. Lay out remaining salsa, chicken mixture, refried beans, lettuce, Mexican cheese, bell peppers, and tomatoes in nice serving bowls and allow diners to fill their own tacos.