Preheat your oven to 375°F (190°C).
Place the chicken breast in a small pot of simmering water and cook for 12-15 minutes until opaque, then shred using two forks.
Heat olive oil in a skillet over medium heat and sauté the diced onion and minced garlic until translucent and aromatic.
In a mixing bowl, combine the shredded chicken, sautéed onion and garlic, half of the diced green chiles, cumin, salt, and pepper.
Spread 2 tablespoons of the green enchilada sauce on the bottom of a small baking dish.
Briefly warm the corn tortillas in a dry skillet or microwave to make them pliable.
Divide the chicken mixture between the tortillas, roll them up tightly, and place them seam-side down in the baking dish.
Pour the remaining green enchilada sauce and the rest of the diced green chiles over the top.
Bake for 15-20 minutes until the sauce is bubbling and the edges of the tortillas are slightly crisp.
Top with sliced avocado, fresh cilantro, and a squeeze of lime juice before serving.