Add the water with the bay leaves and the peppercorns, use a tea infuser if necessary. Wash the carrots, leek and celery and cut to size as desired, but not too big if possible. Then put the vegetables with the chicken breast fillets in the pot and simmer for a good 10 minutes.
In the meantime, clean and quarter or slice the mushrooms, drain the asparagus. Prepare the peas.
Scoop the vegetables and meat out of the pot with a sieve ladle. Dice the chicken breast fillets. Mix the cornstarch with milk and thicken the stock in the pot with it. Then put the vegetables, meat, mushrooms, peas and asparagus back into the sauce. Bring everything to the boil, but not too long so as not to overcook the peas and asparagus. Season with salt and serve with rice or potatoes.
Tip: If you want to do without the cornstarch, you can also puree the soft soup vegetables and use them to thicken the stock, it works wonderfully.