Portobello Tacos

Bahan-bahan (12 porsi)

• 4 portobello mushroom caps (about 12 ounces)
• 1/4 cup olive oil, plus more for sautéing
• 1 tablespoon low-sodium soy sauce
• 1 teaspoon each: chili powder, garlic powder, ground cumin
• fine sea salt and freshly-ground black pepper
• 1 batch refried beans
• 12 small corn tortillas, warmed
• toppings: avocado, chopped cilantro, chopped red onion, crumbled cotija cheese, limes, salsa verde