Spanolatkes

Name: Spanolatkes
Ingredients: 3 tablespoons vegetable oil, plus more for frying; 3 ounces spinach, stems removed, chopped (about 4 cups); 2 leeks, white parts only, thinly sliced; Kosher salt; 4 scallions, thinly sliced (about 1/2 cup); 1 pound russet potatoes; 3 large eggs; 2 tablespoons all-purpose flour; 1/4 cup fresh dill, chopped; 1 cup crumbled feta cheese; Freshly ground pepper; Tzatziki, for serving (optional)