Incredibly delicious fried mushrooms with vegetables! Easy and fast!

Ingredients:
Mushrooms 400 gr.
vegetable oil.
Onion 1 piece
30 grams of butter.
1 large pepper.
1/2 chili pepper.
Sauce:
1 teaspoon sugar.
2 tablespoons soy sauce.
1 tablespoon rice vinegar.
1 tablespoon ketchup.
2 cloves of garlic.
Season with salt and pepper.
A bunch of parsley.
Bon appetit!