For the onions, heat a few inches of oil in small pot over medium-high heat. While that heats up, cut 2-inch thick slices of onion and separate into 4 large rings, reserve remainder of onion for another use. Place buttermilk in a bowl and soak rings a few minutes in the buttermilk. Dredge rings in flour mixed with chives and lots of salt and coarse pepper, then dip them again in the buttermilk and again in the flour. Fry 1 or 2 rings at a time about 4 minutes until deep golden and cool/drain or rack.