Heat the coconut oil in a large nonstick skillet. Toss in the diced onion and salt and sauté for about 5 minutes.
Sprinkle in the ground cumin and dried oregano.
Add the minced chipotle and garlic and sauté until the garlic is fragrant, about 30 seconds.
Pour in the milk and stir the mixture to combine.
Once the mixture has bubbled and reduced slightly, mix in the shredded chicken until evenly coated.
Spoon the mixture evenly onto butter lettuce leaves. Top with pico de gallo salsa and serve.
*Note: You can use skim or low-fat milk instead of whole milk, but make sure to reduce it on a lower heat to avoid curdling the milk! (The lower the fat content, the less stable the milk - therefore, it will curdle much quicker.)