"I bought a selection of lamb cuts from a CSA and got several one-pound packages of ground lamb. I made the last one tonight, and it was the best of all. Top them with Dijon mayo, tomato slices, and baby greens."
Preheat grill for medium heat and lightly oil the grate.
Thoroughly mix ground lamb, rosemary, thyme, garlic powder, salt, and pepper together in a bowl; shape into 4 patties.
Cook the burgers until they are beginning to firm and are hot and slightly pink in the center, about 5 minutes per side. An instant-read thermometer inserted into the center should read 140 degrees F (60 degrees C). Alternately, you can cook the burgers to your desired degree of doneness. Rest burgers while assembling toppings.
Mix mayonnaise and mustard together in a small bowl; spread 1 tablespoon of the mixture onto one side of each bun. Put a burger onto each bun and top with tomato and greens. Sandwich with remaining bun half to serve.