Heat a frypan, melt the butter, and sautee eschalot until soft; set to the side cool. Combine cooled Eshallots with beef, tarragon, Dijon mustard, garlic, egg, breadcrumbs, salt, and pepper in a bowl.
Shape into 12 small burger patties and refrigerate for an hour.
Heat a frypan, cook the burgers to your liking, assemble them with your favorite burger toppings. I used tomato relish, gruyere cheese, cos lettuce, and mini gherkins.