Sprinkle beef evenly with ½ teaspoon salt
and ¼ teaspoon pepper. Brown fillets in hot
oil in an ovenproof or cast-iron skillet
over medium-high heat 3 minutes on each
side. Remove fillets, reserving drippings in
Melt butter in drippings over
medium-high heat. Add yellow and red onion
rings, and sauté 5 minutes.
onions, shallots, and garlic, and sauté 10
to 15 minutes or until lightly browned.
Stir in cognac and broth; cook over
medium-high heat, stirring constantly, until
liquid evaporates (about 5 minutes). Place
fillets on top of onion mixture in skillet.
Cover with aluminum foil.
Bake at 400° for
15 to 20 minutes or until a meat thermometer
inserted into thickest portion of meat
registers 135° (medium rare).
fillets from skillet, reserving onion
mixture in skillet; cover fillets loosely,
and let stand at room temperature 10
Cook onion mixture over medium
heat, stirring constantly, 5 minutes or
until liquid evaporates.
Add salt and pepper to taste. Serve with