Adapted from Sunday Suppers at Lucques by Suzanne Goin
Makes 6 burgers
Just before grilling, generously season both sides of each patty with salt and pepper. Brush the burger patties with olive oil, then arrange the burgers over the hottest area of the grill, over direct heat. Grill, uncovered, without pressing down on the patties (For some reason, people always want to do this. They think it speeds up the cooking time. But all it accomplishes is to squeeze out precious juice). Cook until well seared on the first side, about 3-4 minutes. Flip the burgers over with a metal spatula, top each with about a slice of Manchego cheese, then continue cooking - about 3-4 more minutes, until the pork is just cooked through. (It should remain slightly pink in the center.)
Slice the buns in half, then brush the insides evenly with extra-virgin olive oil. Right after you’re done grilling the burgers, toast the buns on the grill, cut side down, until lightly browned, about a minute.
Spread aioli on both sides of the bun. Place a burger, cheese side up, on the bottom bun, then top the burger with a generous dollop of romesco sauce. Arrange a generous bunch or arugula over the romesco, then top with the top half of the bun. Serve immediately.