Add everything but the chicken to a mixing bowl and whisk well to combine.
Add the chicken breasts to a 9x13 baking dish or gallon zip top bag and add the marinade. Stir well to coat the chicken.
Marinate the chicken in the refrigerator for at least 30 minutes and up to 8 hours. The longer the chicken marinates, the more flavorful it will be.
Heat the grill to a medium heat.
Remove the chicken from the marinade, letting much of it drip off the chicken, and add it to the hot grill.
Grill for 5-10 minutes per side, until cooked through, depending on the thickness of your chicken.
Notes
Olive oil works well in place of avocado oil, if that's what you have on hand. This recipe is also good with chicken thighs.Serve with extra ranch for dipping, if desired.