Combine onions, broth, butter, sugar and salt in skillet. Bring to boiling. Reduce heat to medium. Cover; simmer, shaking skillet occasionally, until onions begin to brown, about 8 minutes. Slowly add Cognac to avoid flaming; cook, stirring, until sauce thickens slightly, 3 minutes. Remove from heat; keep sauce warm.
Sprinkle both sides of steaks with pepper and salt, pressing to adhere.
Heat oil in large heavy skillet over high heat. Add steak; cook 5 to 6 minutes on each side for rare. Transfer to platter. Spoon sauce over steaks. Garnish with parsley. Serve with Sesame Steak Fries. Makes 4 servings.