# Mix the grated onion with olive oil and yogurt.
# Place the beefsteaks on a large plate and flatten them.
# Pour the mixture over the beefsteaks and let it stand in fridge overnight.
# Cook the rested beefsteaks with peppers and tomatoes on a grill. Drizzle salt and black pepper.
# Garnish with sliced onion and serve.
Note: You can cook grilled lamb on skewers by using the same mixture.