For the tuna with chili and tomatoes, cut the chili in half, remove the seeds according to your preference of spiciness and cut into small pieces. Cut the tomatoes into small pieces, chop the garlic.
Mix cane sugar, lime juice, salt and oil well to make a marinade. Mix tuna with garlic and chili. Pour the marinade over it and let it sit for about 15 minutes.
Serve the tuna with chili and tomatoes as desired.