1/2 small red onion, finely chopped
2 tsp. grated lemon zest plus 1/4 cup juice
900gms sweet potatoes, well-scrubbed and sliced into 1/4-in.-thick rounds
3 tbsp. olive oil, divided, plus more for serving
Kosher salt and pepper
1 small fresno chile, seeded and finely chopped
1/4 c. fresh mint, chopped
Plain Greek yogurt, for serving
Heat grill on medium. In small bowl, combine onion and lemon juice. Let sit, tossing occasionally.
In large bowl, toss sweet potatoes with 2 tablespoons oil and 1/4 teaspoon each salt and pepper. Grill until slightly charred and tender, 4 to 5 minutes per side.
Into bowl with onions, stir lemon zest, chile, and remaining tablespoon oil, then stir in mint. Makes 1/2 cup relish.
Spread Greek yogurt (if using) onto a platter and drizzle with oil. Arrange sweet potatoes over yogurt and spoon mint relish on top.