Melt 4 tablespoons butter in large saucepan over medium-high heat.
Add corn, bell pepper, shallot, 1¼ teaspoons salt, and ¼ teaspoon pepper and cook, stirring occasionally, until softened, 5 to 8 minutes.
Add milk and water and bring to boil. Slowly whisk in grits. Reduce heat to medium-low, stirring often, until grits are thick & creamy, 5 to 7 minutes.
Off heat, stir in lemon juice and season with salt and pepper to taste. Cover and set aside.
Meanwhile, combine lemon zest, Old Bay, and 3 tablespoons butter in small bowl.
Sprinkle salmon all over with remaining ½ teaspoon salt and ½ teaspoon pepper.
Melt remaining 1 tablespoon butter in 12-inch nonstick skillet over medium-high heat.
Add salmon and cook until well browned and centers of fillets register 125 degrees (for medium-rare), about 7 minutes per side.
Divide grits among serving bowls.
Arrange salmon fillets over grits and immediately dollop with butter mixture.
Serve with lemon wedges.
