For sauce, in a medium saucepan cook sugar over medium-high heat until it begins to melt, shaking the pan occasionally (do not stir). Reduce heat to low; add onion and garlic. Cook and stir for 5 minutes more or until mixture is golden brown. Bring beer just to boiling in a small skillet. Carefully and gradually add boiling beer to sugar mixture, stirring constantly. Whisk in tomato paste, Worcestershire sauce, vinegar, habanero sauce, chipotle peppers, and salt. Bring to boiling; reduce heat. Simmer, uncovered, for 15 to 20 minutes or to desired consistency. Set aside.
For a charcoal grill, grill steaks on the rack of an uncovered grill directly over medium coals until desired doneness, turning once and brushing with some of the sauce during the last few minutes of grilling. Allow 10 to 12 minutes for medium-rare (145 degree F) or 12 to 15 minutes for medium doneness (160 degree F). (For a gas grill, preheat grill. Reduce heat to medium. Place steaks on grill rack over heat. Cover and grill as above.)
Pass remaining sauce with steaks. Cover and chill any remaining sauce for up to 1 week. Makes 4 servings.