3. Heat olive into a frying pan. Fry the onions stirring occasionally for about 10-15 minutes.
4. Spray the grill with cooking spray and heat to medium high heat. Once the grill is hot cook the burger patties for about 3-4 minutes per side. Once the burger is almost done place a slice of white cheddar onto the patties. Melt the cheese and remove the burgers from the grill.
5. To assemble the burgers, place smashed avocados onto bottom bun, next place the patty on top, spread chimichurri over top and garnish with grill onions.
6. Serve immediately with a side of fries