Preheat oven (electric cooker: 200 °C/circulating air: 180 °C/gas: see manufacturer). Peel onion and garlic. Cut the onion into fine rings and finely dice the garlic. Wash and clean the salad and cut into fine strips. Wash tarragon, shake dry and remove leaves.
Dab the meat dry, brush all around with 1 tablespoon of olive oil and sprinkle evenly with pepper. Season with salt. In a hot frying pan, fry strongly on each side for about 1 minute. Remove the meat and cook in a hot oven for about 8 minutes.
Boil the meat frying pan with 100 ml of water and boil down vigorously for about 2 minutes. Gradually add herb butter in cubes and fold in. Season sauce with salt and keep warm.
In the meantime heat 1 tablespoon of oil in a pot. Fry the onion and garlic in it. Add peas, pour 100 ml water, stir in broth and let everything simmer covered for about 3 minutes. Mix salad strips and tarragon with the peas. Season to taste with salt and pepper.
Cut the meat open, arrange with the pea vegetables and sprinkle with herb sauce.