Steam butternut squash until tender, about 20 minutes (on stovetop with steamer basket)
Puree squash using a food mill or blender. Add salt and pepper to taste (about ¼ tsp salt, about ¼ tsp pepper). Set aside.
Heat drained black beans in a large nonstick pan for about 3-5 minutes, over medium-high heat.
Add taco seasoning and water. Bring to a boil and simmer until almost all water is absorbed. Lower heat.
After beans are prepared, in a small pan, heat tortilla for about 1-2 minutes on each side.
For each tortilla, after heated - spread 2-3 small spoonfuls of squash puree on tortilla. Add ¼ cup black beans on top of puree. Place 2-3 tbsp of salsa on top. Sprinkle with cilantro, red onion, and red cabbage.