Heat 1 tbsp vegetable oil in large nonstick skillet over medium-high heat. Add onion and a pinch of salt and pepper and cook until charred, 3 to 5 minutes each side. Transfer charred onion to medium bowl and cover to keep warm. (4-serving meal: use 2 tbsp vegetable oil)

Return same skillet to medium heat with 1 tbsp vegetable oil and garlic. Cook until garlic begins to brown, 1 to 3 minutes. Add black beans, mojo rojo, mango chutney, jalapeño, and ½ cup water. Mash half the beans with back of fork and cook until water has reduced and mixture begins to thicken, 3 to 4 minutes. (4-serving meal: use 2 tbsp vegetable oil, 1 cup water)

Wrap tortillas in clean dish towel and warm in microwave for 15 to 30 seconds to soften. Divide warm tortillas between plates and top with mango mojo black beans. Top tacos with charred onion, avocado, and cilantro. ¡Buen provecho! (TIP: You can also wrap tortillas in foil and place in 400°F oven until heated through, 5 to 6 minutes.)