Place grated zucchini in a colander; sprinkle with salt and let stand 30 minutes. Press with paper towels to remove as much liquid as possible; zucchini should be fairly dry and reduced to about 2 cups.
Mix egg, zucchini, bread crumbs, green onions, bell pepper, seafood seasoning, mustard, mayonnaise, and red pepper flakes in a large bowl. Form into 8 patties, 3 to 4 inches across.
Heat oil and butter in a skillet over medium-high heat. Fry patties until golden brown, about 4 minutes per side. Drain on paper towels.
