Heat your grill on high for at least 10 minutes, then reduce the heat to medium.
In a large bowl, whisk the egg. Add the turkey, quinoa, bbq sauce, cumin, garlic, salt, and red pepper flakes (if using). Divide the mixture into 4 sections and form 4 large patties (or make 5-6 smaller patties). They will be soft, but don’t worry! Brush olive oil on top to prevent sticking, then place on the grill and cook covered for 3-5 minutes, or until you have nice grill marks.
Brush the other side with olive oil, then flip and spread some BBQ sauce on top of each burger and top with cheese. Cover and cook for 3-5 more minutes, or until cooked through and the cheese is melted.
Place lettuce on the bottom bun and the burger on top. Add whatever other toppings you like! I like to top with lettuce, tomato, jalapenos, and mashed avocado.