Mix yoghurt, vinegar and milk, season with salt and pepper. Cook peas in little boiling water for 2-3 minutes. Drain, rinse with cold water and let drain. Wash chicken fillets, dab dry, season with salt and pepper.
Heat oil in a coated pan, fry fillets on each side until golden brown. Fry for approx. 10 minutes, turning over. Wash the lemons, dab dry. Peel the zest from one lemon with a zest ripper.
Halve the lemon, squeeze the juice. Cut the other lemon into slices. Clean, wash and cut the salad into strips. Wash, clean and halve the tomatoes. Clean, wash and cut spring onions into rings.
Mix lettuce, tomatoes, onions and peas with the sauce, season with salt and pepper. Roast the bread in a toaster until golden brown. Add quince jelly to the chicken 2 minutes before the end of the roasting time. Melt in the pan over a mild heat.
Add the lemon slices and zest and fry. Season the sauce with salt, pepper and 2-3 tablespoons of lemon juice. Serve chicken fillet with sauce and salad. Garnish with chervil.