In large bowl, stir Bisquick mix, 3/4 cup of the cheese, the dill and lemon peel. In small bowl, stir milk, oil and egg with fork or whisk until blended. Make well in center of Bisquick mixture; stir in egg mixture just until dry ingredients are moistened. Stir in onion and salmon. Divide batter evenly among muffin cups, filling each two-thirds full. Sprinkle evenly with remaining 1/2 cup cheese.