Step 1

Place a rack in middle of oven and set a rimmed baking sheet on rack. Preheat oven to 450°. Toast 2 tsp. cumin seeds, 2 tsp. fennel seeds, 1 tsp. coriander seeds, and ¼ tsp. black peppercorns in a dry small skillet over medium-high, stirring constantly, until fragrant and seeds are a shade darker, about 1 minute. Transfer to spice mill or mortar and pestle and let cool slightly; reserve skillet. Grind spices to a fine powder.

Step 2

Transfer spice mix to a large bowl. Add 1 lb. ground turkey, preferably dark meat, 1 medium zucchini, coarsely grated (about 2 cups), zest of 1 lemon, 1 large egg, beaten to blend, 1 serrano chile, seeds and ribs removed if desired, finely chopped, 1¼ cups finely chopped tender herbs, ¾ cup panko, 2 tsp. Diamond Crystal or 1¼ tsp. Morton kosher salt, and 1 tsp. garlic powder. Mix with clean hands until blended (do not overmix). Lightly oil your hands with extra-virgin olive oil and divide meatball mixture into 16 portions, then roll into balls and place on a large plate.

Step 3

Toss 1 lb. green beans, trimmed, with ¼ cup extra-virgin olive oil and 1 tsp. Diamond Crystal or ½ tsp. Morton kosher salt in another large bowl to coat. Carefully remove baking sheet from oven; spread out green beans on baking sheet. Nestle meatballs among green beans, spacing evenly apart and ensuring good contact with pan (it's okay if the beans and meatballs touch). Return baking sheet to oven and bake until green beans are bright green and meatballs have lost their pink color, 8–10 minutes. Heat broiler. Broil, rotating baking sheet halfway through, until green beans are beginning to char in spots and meatballs are browned and cooked through, about 5 minutes.

Step 4

While the meatballs are cooking, heat 2 Tbsp. extra-virgin olive oil in reserved skillet over medium until hot but not smoking. Remove from heat, add ½ tsp. ground turmeric, and swirl pan to combine. Scrape turmeric oil into a small bowl and add 1 cup plain whole-milk Greek yogurt, ¼ cup tahini, stirred well, 2 Tbsp. fresh lemon juice, and 1 tsp. Diamond Crystal or ½ tsp. Morton kosher salt; whisk until smooth. Taste yogurt sauce and add more salt and/or lemon juice if needed. Drizzle with more oil and top with toasted sesame seeds (if using).

Step 5

Serve meatballs and green beans straight from baking sheet or transfer to a platter. Serve with yogurt sauce alongside.Do Ahead: Meatballs can be formed 1 day ahead; cover and chill. Sauce can be made 2 days ahead; cover and chill.