Preheat oven to 400℉. 

Prick sweet potatoes all over with a fork. Roast on a rimmed baking sheet, turning once, until flesh is soft and yielding, 45–55 minutes.

Meanwhile, heat a large Dutch oven or large saucepan, lightly coated with 2 tablespoons evoo, over medium heat. Brown carrots, onion, and pepper until golden brown. Add garlic and cook, stirring constantly, for 1 minute until fragrant. 

Add tomato paste, cumin, chili powder, tomatoes, lentils and water. Reduce heat to simmer and cook, uncovered, stirring occasionally for about 1 hour or until lentils have softened but still maintain texture. Adjust seasoning with salt and pepper. 

When sweet potatoes are ready, allow to cool while preparing garnishes. 

Slice sweet potatoes in half lengthwise and scoop out a bit of potato flesh to make space for the chili. Add the potato flesh to the chili and mix well.

Serve chili over sweet potatoes and topped with garnishes of choice.