Remove the stems and scrape the dark gills from 6 portobello mushrooms. Slice into strips. Measure ½ cup of chopped cilantro.
Toss the mushrooms with half the cilantro, ¼ cup of olive oil, ¼ cup of lime juice, 2 teaspoons of minced garlic, 1 teaspoon of chili powder, 1 teaspoon of kosher salt, ½ teaspoon of ground cumin, and ¼ teaspoon of dried oregano.
Cook in a large nonstick skillet over medium-high heat for 10 minutes, stirring occasionally. Transfer to a bowl.
Finely shred ½ small red cabbage. Toss with ½ cup of mayonnaise and the remaining cilantro. Refrigerate while cooking the peppers.
Heat 1 tablespoon of olive oil in the skillet. Cook 2 sliced bell peppers for 10 minutes, until soft. Return the mushrooms and stir for 1 minute.
Fill 12 small warm tortillas with the slaw and mushroom mixture. Serve immediately.
