Preheat grill to medium heat.

In a mixing bowl, drizzle olive oil over the ground bison.

Add kosher salt and freshly ground pepper to the bison.

Remove rosemary leaves from one spring and roughly chop.

Add the chopped rosemary to the bison mixture.

Gently mix all ingredients together.

Form the mixture into equal sized patties about 1-inch thick and 5 inches in diameter.

Place a thumb imprint in the center of each patty about halfway through the thickness of the meat.

Cook the burgers over medium heat for 2-3 minutes per side.

Check for doneness when the burger releases easily from the grill and is nicely browned.

Flip each burger and add a slice of fresh buffalo mozzarella on top.

Lightly toast the buns on the grill while the burgers cook for another 2-3 minutes, until the mozzarella is melted.

Remove the toasted buns and spread green olive tapenade on the top bun.

Stack lettuce leaves, tomato slices, and the burger on the bottom bun.

Place the tapenade-covered top bun on the burger and serve immediately.