In a large skillet, heat 1 tablespoon of olive oil over medium heat. Once hot, add the sliced onion, stirring occasionally until it becomes translucent and soft, about 5-7 minutes.

Next, stir in 2 minced cloves of garlic and sauté for another minute.

Add the 2 diced tomatoes to the skillet, mixing well with the garlic and onions. Allow the tomatoes to soften for about 5 minutes, stirring occasionally.

Now, mix in the 2 chipotle peppers in adobo sauce, along with 1 teaspoon each of cumin and oregano, along with salt and pepper to taste.

Pour in the 2 pounds of shredded chicken, using a spoon or spatula to mix it well with the sauce.

Reduce the heat and let the mixture simmer for 15 minutes.

To serve, spoon the Tinga de Pollo into warm corn tortillas, garnishing with fresh cilantro and avocado slices.