In a small nonreactive bowl, combine onions, lime juice and Tabasco ; cover and refrigerate for at least 2 hours but less than 6. Rub meat all over with pepper and salt. Sprinkle half the flour on each side of the meat. Saute over high heat in a large saute pan, with no oil, until well sea red, 5 to 7 minutes on each side for rare. Remove from heat and serve in thickish slices, topped with generous portion of t he marinated onions. Per serving: 210 calories, 5 grams fat.