Start by making the sauce. Combine all of the sauce ingredients in a bowl and mix well with a whisk. Refrigerate while you make the burgers.
Form beef into burger patties. You want very thin patties, about 1/4 inch thick. 1 lb of beef will make about 4 of these patties. They will be very large and thin (but will shrink a lot when cooking). Season the patties with salt and pepper on both sides and set aside.
Slice onion as noted and heat a medium skillet over medium-low heat and add 1 tbsp of ghee. Add the onion to cook, stirring occasionally, until browned and caramelized. This should take about 15 minutes and be finished about the same time as the burgers. If they cook to fast or finish early, just simmer on low until the burgers are ready.
Prep the toppings for the burgers as noted. For the buns, cut the iceberg lettuce head into fourths. Cut off the bottom “stem” of each wedge of lettuce. Remove the thick inner pieces, leaving the outer leaves. You’ll split these leaves to form your top and bottom “bun”.
Cook over medium-high heat on a grill or heat a large skillet over medium-high heat and add 1 tbsp ghee. Once the ghee is hot and shimmering (or the grill is hot), add the burgers to cook for 3-4 minutes per side, or until cooked to your liking. If using a skillet, you may have to cook burgers in batches, two at a time.
Now, assemble your burgers. Put 1/2 of the lettuce wedge on a plate and add a tomato slice and some pickles at the bottom. Top with a burger patty and spread some sauce over the top. Add on some onions and top with more sauce if desired. Top with the other 1/2 of the lettuce wedge to form a burger. Pick it up with both hands and enjoy!