In a small bowl, combine the mango, salsa, cilantro and onion; set aside.
Separate 2 eggs. In a large bowl, combine the flour, cornmeal, baking powder, salt and pepper. In another bowl, whisk the remaining eggs, egg yolks, cream-style corn, milk and butter. Stir into dry ingredients just until blended. Fold in corn and onions. In a small bowl, beat egg whites and cream of tartar until stiff peaks form. Fold into batter.
Pour batter by 1/4 cupfuls onto a greased cast-iron skillet or hot griddle. Cook on each side or until golden brown, 2-3 minutes.
Meanwhile, place 2-3 in. water in a large skillet with high sides; add vinegar. Bring to a boil; reduce heat and simmer gently. Break cold eggs, 1 at a time, into a custard cup or saucer; holding the cup close to the surface of the water, slip each egg into water.
Cook, uncovered, until whites are completely set and yolks are still soft, about 4 minutes. With a slotted spoon, lift eggs out of water. Serve with corn cakes and salsa.