Mix the cornmeal, flour, baking soda and salt. Whisk the eggs, milk, and butter together and combine with the dry ingredients into a batter. Allow the batter to rest, refrigerated, for 30 minutes. Heat the vegetable oil in a large saute pan over medium heat until a little a batter dropped in begins to sizzle. Begin to spoon in batter, 2 to 3 tablespoons at a time to make pancake-like corncakes. Cook in batches, cleaning the pan if it becomes messy and adding additional; oil if necessary. Keep the cakes warm while you finish cooking the remaining batter. Combine the sour cream with the chopped chives and serve several corncakes with a dollop of sour cream and a dollop of salmon roe. Garnish with a small salad and whole chives.