Step 1: Fry onion in a small amount of oil until golden, then add minced meat until browned. Add mushrooms and bell pepper and cook together.
Step 2: Add salt, pepper, turmeric, and tomato paste. Mix well, then remove from heat.
Step 3: Boil lasagna sheets in salted water with a little oil for 10 minutes until soft. Drain and rinse with cold water.
Step 4: Combine milk with flour and a pinch of salt. Heat until slightly thickened, then remove from heat.
Step 5: In a baking dish, layer lasagna sheets, meat mixture, and cheese. Repeat layers until all ingredients are used. Pour milk sauce on top and add extra cheese.
Step 6: Bake in a preheated oven at 180°C (350°F) for 30 minutes or until golden and bubbly.