Recipes: Tuna tacos with onions

Preparation:  Preparation time: 15 mins Cooking time: 15 mins Serving: 4 Ingredients: 3 tablespoons olive oil 2 medium red onions, thinly sliced Salt 1 teaspoon chipotle powder or hot paprika 1 teaspoon dried oregano 1 tablespoon red wine vinegar 1 ripe mango—peeled, pitted and cut into 1/4-inch dice 1 medium...