Defrost the peas. Peel and chop the onion. Heat 4 tablespoons of oil in a saucepan. Cover peas and onions and stew for 4-5 minutes. Clean and wash the celery, put some celery green aside for garnishing.
Peel and wash the carrot. Cut celery and carrot into small cubes. Heat 2 tablespoons of oil in a frying pan. Fry the vegetables and minced meat for 4-5 minutes, turning them over. Pour in wine and simmer until the wine has evaporated.
Add the tomatoes and simmer covered for 30-40 minutes. Add some water in between. Cut ham into small pieces. About 3 minutes before the end of the cooking time add peas, onion and ham to the minced sauce, season with salt and pepper.
For the béchamel sauce, melt the fat, dust with flour, sweat and stir in the milk. Bring to the boil, simmer for 1-2 minutes, season with salt, pepper and a little nutmeg. Bring a saucepan with plenty of salted water to a boil.
Add the lasagne sheets, simmer for about 1 minute, remove and rinse in cold water. Grate the parmesan. Grease the casserole dish, line the bottom with 3 lasagne sheets. Put 1/3 of the minced meat on top, sprinkle with some parmesan.
Repeat the process twice more. Finish with lasagne plates. Pour the béchamel sauce over it and sprinkle with the remaining Parmesan cheese. Bake in the preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: level 3) for 25-30 minutes until golden brown.
Remove, arrange and garnish with celery green.