Heat an 8-inch skillet over medium-high. Combine the beans, 1/4 cup water and ground cayenne in the skillet and whisk until smooth. Reduce heat to low and cook until warmed through and just starting to bubble. Sprinkle the Oaxacan-style cheese on top and warm until melted, about 3 minutes.
Meanwhile, heat the tortillas one-by-one over an open flame (or in a hot skillet, if you don’t have a gas stove). Wrap them tightly in a clean kitchen towel, stacking and rewrapping as you go to keep them warm as you heat each one (or, you can use corn chips).
Remove the beans from the heat and garnish with the avocado, radish, and snap peas/lettuce in even layers. Sprinkle with grated cheese. Serve with warm tortillas and lime wedges for squeezing over the tacos.