Remove the chicken from the fridge and set it on the counter for about 15 minutes while your grill is preheating. This will help ensure the cutlets cook evenly.
Preheat the grill to medium-high heat.
Arrange your items for the grill. Using a pastry brush, coat the onion rounds with avocado oil and a pinch of salt and pepper. You will also need to bring out the cooked bacon pieces, the cheddar cheese, sourdough slices, and the garlic clove.
Once the grill is hot, remove the chicken from the marinade, allowing the excess to drip off and add directly to the grill. Cook undisturbed for 4 minutes before flipping to the other side. Flip, and cook for another 3-4 minutes, until the chicken has grill marks and is fully cooked through (registering 165 when using a thermometer). This will vary depending on the thickness of the cutlets.
Add 4 small pieces of bacon to each cutlet and top with the sliced goat cheddar cheese. Turn the heat down to medium, close the lid, and allow the cheese to melt for about 2 minutes before removing the cutlets from the grill and transferring them to a clean plate. Allow to rest.
Add the onions and cook for 4 minutes per side. Once cooked, transfer to a plate.
Turn the grill down to medium-low. Brush the sourdough with avocado oil and transfer it to the grill. Toast for about 1 minute per side until the bread is slightly golden but soft in the middle. Remove from the heat and immediately rub the raw garlic into the bread's surface. Turn off the grill.