Combine sour cream and chives in a small bowl. Cover and chill.
Cut kernels from ear of corn. Scrape remaining pulp from cob using the dull side of a knife blade. Discard cob. Set corn aside.
Lightly spoon flour into a dry measuring cup; level with a knife. Combine flour and cornmeal in a medium bowl; make a well in the center of the mixture. Combine milk and egg yolk in a small bowl, stir well with whisk. Add milk mixture to flour mixture, and stir with a whisk until just moist. Stir in corn, salt, and pepper.
Place egg white in a bowl, beat with a mixer at high speed until foamy. Gently fold egg white mixture into corn mixture.
Heat a large nonstick skillet over medium heat. Coat pan with cooking spray. Spoon 1 tbls. batter per blini onto pan, spreading to about 2" diameter. Cook 2 minutes or until tops are covered with bubbles and edges begin to set. Carefully turn blinis over, cook for 1 more mintue. Transfer blinis to a serving platter, and arrange in a single layer; keep warm. Repeat process with the remaining batter. Top each blini with with 1 piece salmon and 1 teaspoons sour cream mixture. Garnish with chopped chives, if using.