HEAT oven to 325ºF.
HEAT oil at medium-high in a large skillet.
ADD carrot, scallion whites, chili powder and half of the tomatoes.
COOK until tomatoes are soft. Add sausage and cook until it begins to brown.
ADD scallions and cook until most of the liquid has evaporated.
WARM taco shells on a baking sheet in the oven for 6 minutes.
MIX mango with lime juice in a medium bowl; sprinkle with chili powder.
ADD remaining tomatoes and scallion greens and toss.
FILL taco shells with sausage mixture. Top with lettuce, cheese, mango salsa and scallion greens.