In a medium saucepan over medium-high heat, bring 4 cups water to a boil. Add bouillon, stirring until dissolved. Add chicken; cook until cooked-through, about 20 minutes. Transfer to refrigerator until cold. Shred chicken.
Heat a large skillet over medium-high heat. Once warm, add the oil and onions. Cook for about 4 minutes or until translucent, stirring occasionally. Add in garlic and cook for 30 seconds more. Stir in chipotles with sauce, oregano, cumin toast for about 2 minutes. Add tomato sauce and simmer until flavors are combined.
Once sauce has simmered add chicken and salt and cook until chicken is reheated. Taste to add more salt if necessary.
In a lightly greased skillet set over medium-high heat, warm tortillas for 15 to 30 seconds per side. Assemble chicken in tortillas and serve with avocados, queso, onions, cilantro and lime wedges.