For salsa, combine tomatoes, mango, avocado, green onions, habanero pepper, fresh cilantro, olive oil, and juice and grated zest of lime in non-reactive bowl. Let stand 15 minutes at room temperature before serving.

For steak, in small skillet combine cumin and coriander seeds; toast over high heat for 1 to 2 minutes or until fragrant, stirring occasionally. Transfer spices to a spice grinder or mortar (with pestle). Process until finely ground. In a small bowl combine ground spices, sugar, garlic salt, and red pepper flakes. Rub both sides of steak with oil. Pat 1/2 of spice mixture on each side of steak. Preheat broiler. Place steak on the unheated rack of a broiler pan. Broil 4 to 5 inches from the heat for 8 to 9 minutes (for medium-rare doneness), turning once. (For a charcoal grill, grill steak on the rack of an uncovered grill directly over medium coals for 11 to 15 minutes for medium rare doneness, turning once. For a gas grill, preheat grill. Reduce heat to medium. Place steak on rack over heat and grill as directed above.) Remove meat from broiler or grill. Wrap in foil and let stand 10 minutes. Slice across the grain into very thin slices; cut slices into 2-inch pieces.

To serve, place 1 to 2 steak slices in bottom of tortilla cups; top with heaping tablespoon of salsa. (Note;) If there are vegetarians at the party, skip the steak and just fill the corn cups with 2 tablespoons of the salsa. Makes 16 servings (4 pieces per serving).

Check the ethnic foods aisle at your local supermarket or the bulk spice section at a natural foods store for whole cumin and coriander seeds -- if you can't find substitute 1 tablespoon each ground cumin and coriander in the rub and skip the toasting step.