How to Make It
In a small bowl, whisk the flour with the cornmeal, 1/2 teaspoon salt, 1/4 teaspoon pepper and the baking powder. In a food processor, coarsely chop the corn kernels. With the machine on, add 3 of the eggs and the egg yolk, one at a time, and process until incorporated. Add the melted butter, basil, scallions and the flour mixture and process just until combined. Scrape the batter into a bowl.
Put the onion in a small strainer and rinse under cold water for several seconds. Pat dry and transfer to a small bowl. Stir in the 1/2 cup of crème fraîche and the lemon juice and season with salt and pepper.
Bring a medium saucepan of water to a boil. Add the vinegar. Crack the 4 remaining eggs into the water and poach until the whites are firm and the yolks are runny, about 4 minutes. Remove the eggs with a slotted spoon and keep warm in a bowl of hot water.
Heat a cast-iron skillet. Pour in a thin film of oil and heat until shimmering. Drop heaping tablespoons of the batter in the skillet and cook over moderate heat until bubbles form on the surface. Flip the pancakes and cook for about 1 more minute. Transfer the pancakes to a baking sheet and keep warm in a low oven. Repeat with the remaining batter.
Arrange 3 pancakes on each plate. Top with the poached eggs and a dollop of crème fraîche. Sprinkle with the chives and serve at once.