I add the water, lime juice, chili powder, and cumin to a medium saucepan and set it over medium-high heat. Once it starts to bubble, I stir in the shredded chicken and green onions. I let it cook for about five minutes, stirring often, until everything is heated through and coated in that seasoned liquid.
While the chicken warms, I combine the black beans and salsa in a small microwave-safe bowl. I pop it in the microwave for about 30 seconds, just enough to take the chill off. This little step keeps the burritos from ending up cold in the center once they're assembled.
I lay out my tortillas and spoon about a third of a cup of the chicken mixture into the center of each one. On top of that, I add a sixth of the bean and salsa mixture, followed by a sixth of the shredded cheese. I try not to overfill them, since a stuffed tortilla is much harder to roll neatly.
I fold the bottom third of the tortilla up over the filling first, then fold in both sides toward the middle before rolling it the rest of the way up. This is the technique that keeps everything sealed inside instead of spilling out the moment you pick it up.
I heat a large nonstick skillet or griddle pan over medium-high heat and give it a light spray of cooking oil. I place the burritos seam side down first, so the seam seals shut as it cooks. I let them brown for a couple of minutes per side until they're golden and the cheese inside is fully melted.