Marinate steak in 2 tablespoons soy sauce, 1 tablespoon sherry, and 2 teaspoons cornstarch for 20 minutes. Meanwhile chop onion in half vertically and cut in thin slices; chop pecans and mince chili pepper.
In a 1-cup measure, combine remaining tablespoon soy sauce, 2 tablespoons sherry, 2 teaspoons cornstarch and the sesame oil. Add enough water to make 1/2 cup and mix well to make sauce.
In large skillet or wok, heat oil over medium-high heat. Add onion, broccoli, and red chili pepper; cook, stirring often, 6 minutes. Sprinkle in garlic powder, then add meat and cook, turning frequently, until browned but not completely cooked – 8-10 minutes. Stir in sauce mixture and cook until liquid in pan thickens and coats meat and vegetables – 2-4 minutes. Stir in half the pecans. Divide among serving plates and sprinkle with remaining pecans.
Nutrition information per serving: calories: 470 ; protein: 36g; carbohydrate: 14g; saturated fat: 6g; monounsaturated fat: 13g; polyunsaturated fat: 7g; cholesterol: 76mg; fiber: 4g; sodium: 722mg.