STEP-BY-STEP COOKING RECIPE
Cut the fillet into large cubes, sprinkle with salt, pepper, drizzle with vinegar, add chopped onions, mix and refrigerate for 4-6 hours.
Cut red onion into rings and fry in butter until half cooked, 5 min., Add chopped garlic and fry for another 1 min.
Cut the mushrooms into quarters and fry until half cooked, put the meat taken out of the marinade, and fry until a crust appears.
Add the fried onions, mix, put in a clay pan and bring to readiness in the oven, heated to 220ºС, for 10-15 minutes. Sprinkle with chopped herbs and serve.