Wash and peel the asparagus, cut off the woody ends briefly. Bring 1/2 litre of salted water to the boil. Season with some sugar and a slice of lemon. Let the asparagus skin and asparagus slices simmer for about 20 minutes at medium heat.
In the meantime wash the fillets, dab dry and cut into slices. Heat oil in a pan. Fry the medallions for 2-3 minutes on each side. Season with salt and pepper. Pour asparagus stock through a sieve and bring to the boil again.
Cut the asparagus a little bit smaller and cook them for about 15 minutes. In the meantime, remove the crusts and crumble the toast. Wash basil, shake dry, pluck leaves. Cut into fine strips except for a few for garnishing.
Clean, wash and halve the tomatoes. Peel and finely chop the onion. Drain the asparagus, catch the stock again. Melt 1 tablespoon of fat. Sauté onion in it. Add flour and sauté. Add cream and stock while stirring constantly and bring to the boil.
Season to taste with salt and pepper. Stir in basil cut into strips. Divide the vegetables, meat and sauce into portion moulds. Sprinkle with toast crumbs. Spread 1 tablespoon of fat in small flakes on top.
Bake in the preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: level 3) for approx. 10 minutes. Serve sprinkled with basil leaves.