For the Sauce:
2 cloves garlic
1 inch piece ginger, or more if desired
1 tablespoon tahini
2 lemons, juiced
3/4 cup water
1/2 teaspoon black pepper
2 teaspoons miso paste
For the Vegetables
3 Portobello mushrooms, gills removed, sliced
2 red bell peppers, sliced
1 small yellow onion, sliced
1 bunch green onions, sliced
1/4 cup chopped cilantro