preheat oven to 400°F. In large pot heat 1 tsp vegetable oil over medium high heat. Add garlic and cook till fragrant,30 seconds. Add tomato paste, diced tomatoes and liquid,and chili powder. Cook until most of liquid is evaporated,2 to 3 mins. Add broth and bring to a boil. Season with salt and pepper.

mean while,on a rimmed baking sheet,toss tortillas with 2 tsp oil. bake 8 mins.Divide chicken,avocado,cheese,cilantro,and scallion among bowls. top with tortillas and broth. Serve.