Dice the chicken breast fillet, season with salt and pepper and fry well.
Cut the boiled eggs into large cubes.
Melt the butter and sweat the flour in it until golden. Slowly deglaze with the vegetable stock. Stir continuously until the sauce has the desired consistency. Let the sauce simmer for about 10 minutes. Stir in the mustard and cream. Season with salt, pepper and lemon juice.
Add the meat and eggs to the sauce and let them warm up again.