Grilled Salmon and Peaches with Basil-Pistachio Gremolata

Prepare grill for indirect grilling: Heat one side of a gas grill to medium-high (400 degrees F), or push hot coals to one side of a charcoal grill. Maintain temperature at about 400 degrees F.

Combine cumin, chili powder, sugar, 3/4 teaspoon salt, garlic powder, and red pepper; rub evenly over flesh side of salmon.

Cut onion into 8 wedges, leaving root end intact. Cut each peach in half, remove pit, and cut each half into 4 wedges (16 wedges total). Place onion and peach wedges in a medium bowl; drizzle with oil, and toss gently to coat.

Arrange salmon over hot coals on oiled grill rack (over direct heat); close lid and grill until skin becomes crisp and lightly browned, 4 to 5 minutes. Move salmon to unheated side of grill for indirect grilling: On a gas grill, turn off burners under salmon and turn on burners on the other side of grill; on charcoal grill, carefully rotate grill rack using oven mitts so that salmon is over unheated side of grill. Arrange onion and peach wedges over hot coals on oiled grill rack (over direct heat). Close lid and grill until salmon flakes when tested with a fork and onion and peach wedges are well marked, about 4 to 5 minutes for salmon (no need to flip) and 1 to 2 minutes per side for onions and peaches. Remove from grill; sprinkle onion with remaining 1/4 teaspoon salt. Arrange salmon, peach wedges, and onion wedges on a platter.

Combine pistachios, basil, and lemon zest. Sprinkle evenly over platter.