This will make 12 - 14 sliders. If you want less, just use 1 lb of meat and 1/2 the rest of the ingredients. I used all beef sirloin.
Step 1: Transfer 1/4 cup of the pesto to a bowl. Add the ground chuck and ground sirloin and a pinch of salt and gently knead to blend. Form the mixture into 12-14 small patties, about 3/4 inch thick. Brush the burger patties lightly with olive oil.
Step 2: Mix remaining 1/4 cup pesto with 1/4 cup mayo and set aside.
Step 3: Light a grill and oil the grates. Grill the burgers over moderately high heat for 3-4 minutes. Flip the burgers, top them with the mozzarella slices and close the grill. Cook for 3 -4 minutes longer for medium-rare burgers. Cook longer if you want your burgers done more. Brush buns with oil, grill the buns until lightly toasted, then spread the pesto/mayo mixture on the bottom of buns. Top with the burgers with a tomatoes and a basil leaves. Close the burgers and serve right away.
Paried with Chacras Malbec by Goldschmidt
Adapted from Food & Wine Annual book 2013