Chicken Salad:
Place the chicken meat in a pot with water and simmer for approximately 12 minutes. Drain the water and cool the meat before cutting it into small pieces. Set it aside.
Clean and quarter the mushrooms, sauté them in a bit of oil in a hot pan until golden. Season with salt and pepper. Drain the asparagus in a colander.
Mix crème fraîche with mayonnaise, curry, and mustard. Fold in the chicken, mushrooms, and asparagus. Season to taste with salt, pepper, and lemon juice.
Assembly:
Cut the woody ends off the green asparagus and steam them briefly in lightly salted water for about 2 minutes. Quickly rinse them in cold water to retain their green color.
Quarter the cherry tomatoes.
Slice the croissants open and fill them with the chicken salad. Garnish with asparagus and tomatoes.
Serve immediately.