Salad for Breakfast

Name: Salad for Breakfast
Ingredients: 4 large eggs; 1 teaspoon kosher salt, plus more; 1 tablespoon sugar; 1 teaspoon ground turmeric; 1/2 cup plus 2 tablespoons unseasoned rice vinegar; 2 cups chopped crunchy vegetables (such as cucumbers and radishes); 1/4 sweet onion, very thinly sliced; 8 ounces feta, cut into thick slices; 1/4 cup extra-virgin olive oil, plus more for drizzling; 4 slices sourdough bread, toasted, cooled; 8 cups lettuce leaves, torn if large; Ground sumac (for serving)