Kuku Sabzi

Heat 2 Tbsp. vegetable oil in a 10" skillet over medium. Cook 1 medium onion, finely chopped, and 1 medium leek, white and pale-green parts only, finely chopped, stirring occasionally, until very soft but not brown, 10–12 minutes. Transfer to a plate and let cool. Wipe out skillet; set aside.

Whisk 5 large eggs, 1½ tsp. Diamond Crystal or 1 tsp. Morton kosher salt, 1 tsp. freshly ground black pepper, 1 tsp. baking powder, and ½ tsp. ground turmeric in a large bowl. Using a rubber spatula, mix in reserved onion mixture, 1½ cups finely chopped cilantro, 1½ cups finely chopped dill, 1½ cups finely chopped parsley, and 1 Tbsp. dried fenugreek leaves. (Egg mixture should look thick and very green.)

Preheat broiler. Heat remaining 3 Tbsp. vegetable oil in same skillet over medium. Pour in egg mixture, spreading evenly across pan with spatula. Cover and cook until bottom is just set, 8–10 minutes. Uncover and broil, watching carefully, until top is set, about 1 minute. Let cool slightly, then slide kuku sabzi onto a platter.