Preheat the grill to medium high, ensuring the grates are clean and well-oiled.
This fusion of poultry and pork, with a vegetable herb stuffing, is a great way to build flavor from the inside out.
Put the Portobello mushrooms and onions in a large mixing bowl and drizzle with olive oil.
Add the minced garlic to the mushrooms and onions, seasoning to taste with salt and pepper. Toss to coat evenly.
Lay the seasoned mushrooms, stem-side up, and onions on the grill. Grill mushrooms and onions four to six minutes per side.
Remove both from the grill, chop roughly and splash with balsamic vinegar. Set aside to cool completely.
Cut into the side of the chicken, creating a deep pocket inside the breast, with caution to not pierce through or butterfly the meat.
Gently, but liberally, stuff the chicken with cheese, followed by grilled veggies.
Lay three to four bacon strips per breast on a cutting board, one next to another with no spaces.
Place the stuffed breasts over the bacon strips, tightly rolling and wrapping the chicken.
Insert water-soaked toothpicks through the bacon, securing the wrapping.
Grill for 15-20 minutes over indirect heat, rotating every 5-7 minutes, or until the bacon is crisp and the internal temperature of the chicken reaches 165°F.
Pull the chicken from the grill, set on a cutting board, tent with foil and allow to rest for three to five minutes.
Plate, serve and enjoy!