Combine the beef, garlic and herbs in a bowl. Form 2 patties and rest on a plate for a few hours.
To get started, start caramelizing your onions. Turn the heat over medium-low, add 1 Tbsp of extra-virgin olive oil, 1 Tbsp butter, and the onions. Sauté for about 30 to 45 minutes. Once the onions are shriveled and oozing with deep flavor, you’re done. Remove the onions from the pan and cover to keep warm.
Add the beef patties to the skillet and cook on medium-high, about 5 minutes per side. (Or grill them).
Melt some cheese on the burgs while you toast the buns.
Top burgers with avocado and onions.