For a Sunday brunch treat or anytime you want a hearty steak-and-eggs meal, cook up this protein-rich entrée. Serve with a side salad if desired.
Heat a grill or grill pan. Brush each side of steak with ½ tbsp olive oil; sprinkle with ⅛ tsp each of salt and pepper. Grill steak until browned and an internal temperature reaches 145°F, flipping halfway. let cool before thinly slicing.
In a medium bowl, whisk together eggs, milk, and ⅛ tsp each of salt and pepper.
In an ivenproof skillet, heat remaining 1 tbsp olive oil over medium heat. Add onion and saute until translucent. Add steak and heat until cooked through, about 1 to 2 minutes.
Pour egg mixture over steak, covering evenly. Reduce heat to low, cover, and cook. After about 5 minutes, slightly lit the sides of frittata to allow excess liquid from top to drizzle down. Cook until eggs set, about 5 minutes more.
Sprinkle eggs with cheese, then place uncovered skillet in broiler until cheese has melted and is slightly browned, about 2 minutes.
Cut frittata into 8 wedges.