Mix 1/2 cup steak sauce, 2 tbsp ketchup, 1 tbsp corn syrup, 1 tbsp minced garlic, 2 tbsp minced onion, and 1/2 cup water to prepare the sauce.

Slice zucchini and mushroom into thin pieces, and julienne 1/4 onion.

Make shallow cuts on both sides of the chicken breasts. If unseasoned, add salt and pepper for flavor.

Heat oil in a pan and cook the zucchini and mushroom slices on both sides until tender. Lightly season with salt.

Remove the cooked vegetables and place them on a plate. Add the chicken breasts and julienned onion to the pan.

Pour the prepared sauce over the chicken and onions. Simmer on medium-low heat, flipping the chicken occasionally.

Transfer the chicken to a plate and generously pour the sauce over it.