Another re cope from my Mamma Fichiera, she just made this, and so do I . The amounts are up to your taste, use more or less, change up the ingredients. Everyone absolutely loves it, eat it hot warm or cold
Things you will need:
Large skillet, kitchen string, meat mallet
Preheat oven to 350°F
Butterfly steak by slicing it horizontally from right to left. Do not slice through other side. Open steak and pound with meat mallet until same thickness all over.
The thicker you leave the meat, the longer it will have to cook. The reverse is also true.
Lay meat cut side up on board or counter. Start layers of stuffing,, being careful to leave at least 1/2-1 inch al all edges clear of stuffing materials. I usually start with mozzarella and with hard boiled eggs and mozzarella and Pecorino-Romano as last.
Roll up steak and tie with string at top, middle and bottom. Heat oil in skillet with onions and garlic until fragrant. Place meat in middle of pan and brown all over by turning. When all sides are browned, add salt and pepper to taste to an. Turn off flame, add tomatoes to reach half way up meat. Do not cover with sauce,as flank steak becomes very stringy when boiled ( I found that out he hard way) in 350°F oven check for done ness after 45 min. We like the meat on the rare side.
When meat is fully cooked to your taste, remove from oven. Rest for 10 minutes and slice into 1" circles. Serve hot or cold as an appetizer, or serve at table with a side of spaghetti, using cooking sauce for spaghetti.