Heat a large skillet over medium low heat and swirl in 1 tablespoon of ghee when the pan is hot. Toss in the finely diced shallots and sauté for 3 to 5 minutes or until golden and translucent.
Transfer the sautéed shallots to a bowl to cool to room temperature. If you want to chill the shallots quickly, put them in a single layer on a plate and pop them into the fridge or freezer until you are ready to form the Nomster burgers.
Divide the ground beef into 4 equal portions. Using your fingers, sculpt each portion into a concave bowl.
Tuck about a teaspoon of cooked and chilled shallots into each beef bowl. Then, seal up the hole to form a ball.
Flatten the balls with your hands to make ½-inch thick shallot-stuffed burger patties. (Make ahead tip: you can store these formed patties in the fridge for up to a day at this point.)
When you are ready to fry the Nomster burgers, heat a large skillet over medium high heat. Liberally salt and pepper on one side of the patties.
Swirl 1 tablespoon of ghee in the pan, once it’s hot. Place two patties seasoned-side down in the pan. Sprinkle salt and pepper on the top of the patties and fry undisturbed for 3 minutes or until a nice crust forms on the bottom.
Spread a teaspoon of mustard on the top of each Nomster burger. Flip the patties over, and cook for another 2 minutes or until the desired doneness is reached. Repeat cooking steps for the remaining two patties.
Serve each burger patty with lettuce and tomatoes. If you’re feeling truly Nomstrous, add a crispy fried egg and a generous squirt of sriracha (or ketchup)!