Zest of 1 small lemon
1 garlic clove, finely grated
¼ cup plain whole-milk Greek yogurt
¼ cup tahini
3 Tbsp. fresh lemon juice
2 Tbsp. finely chopped mint
½ tsp. sugar
Kosher salt, freshly ground pepper
BURGERS AND ASSEMBLY
1 Tbsp. coriander seeds
2 tsp. cumin seeds
4 Tbsp. (or more) extra-virgin olive oil, divided
1 small white or yellow onion, finely chopped
2 garlic cloves, finely grated
½ tsp. ground cinnamon
1 large egg
1 cup finely chopped cilantro
½ cup panko
1 tsp. Diamond Crystal or ½ tsp. Morton kosher salt, plus more
Freshly ground pepper
1 lb. ground turkey
4 soft sesame seed buns, split
Torn romaine lettuce, thinly sliced red onion, mint leaves, and hot sauce (for serving)
Stir zest of 1 small lemon, 1 garlic clove, finely grated, ¼ cup plain whole-milk Greek yogurt, ¼ cup tahini, 3 Tbsp. fresh lemon juice, 2 Tbsp. finely chopped mint, ½ tsp. sugar, and 1 Tbsp. water in a small bowl until smooth. Season generously with kosher salt and freshly ground pepper. Chill until ready to serve.
Do ahead: Yogurt sauce can be made 1 day ahead. Cover and keep chilled.
BURGERS AND ASSEMBLY
Coarsely crush 1 Tbsp. coriander seeds and 2 tsp. cumin seeds with mortar and pestle or very coarsely grind in spice mill.
Heat 2 Tbsp. extra-virgin olive oil in a large skillet, preferably cast iron, over medium. Cook 1 small white or yellow onion, finely chopped, stirring occasionally, until softened and translucent, 5–7 minutes. Add spice mixture, 2 garlic cloves, finely grated, and ½ tsp. ground cinnamon; cook, stirring often, until spices are fragrant, about 1 minute. Scrape onion mixture into a large bowl; wipe out skillet and reserve.
Add 1 large egg, 1 cup finely chopped cilantro, ½ cup panko, and 1 tsp. Diamond Crystal or ½ tsp. Morton kosher salt to onion mixture, season with freshly ground pepper, and mix to combine. Add 1 lb. ground turkey and gently mix with your hands until just incorporated (do not overmix). Using damp hands, form into four 4"-diameter patties.
Heat 2 Tbsp. extra-virgin olive oil in reserved skillet over medium-high. Season patties generously on both sides with salt and pepper. Working in 2 batches and adding more oil between batches if needed, cook patties, undisturbed, until deeply browned underneath, about 5 minutes. Flip and cook, undisturbed, until deeply browned on second side and cooked through (an instant-read thermometer inserted into center should register 165°), about 4 minutes. Transfer to a wire rack. Wipe out skillet.
Working in batches, toast 4 soft sesame seed buns, split, cut side down, in same skillet until golden brown and crisp around edges, about 3 minutes. Transfer to rack.
Arrange burgers, buns, torn romaine lettuce, thinly sliced red onion, and mint leaves on plates with yogurt sauce and hot sauce alongside and let everyone build burgers as desired.