For the onion rings, fill a countertop fryer with oil or pour a few inches of oil into a large Dutch oven. Heat oil to 365 F. (The oil is ready for frying when a 1-inch cube of white bread cooks to golden brown in 40 seconds.) Combine buttermilk and sour cream in a bowl and add the onion rings; soak for a few minutes. On a plate, toss the flour with the chives; season generously with salt and pepper. Dip the onion rings in the seasoned powder, then again in the buttermilk, and again in the flour. Fry 1 or 2 rings at a time in the hot oil, turning once, until deep golden, about 4 minutes. Transfer to a rack to cool.
For the burgers, heat a large skillet or griddle over medium-high heat. In a large bowl, combine the beef, Worcestershire sauce, lots of pepper and a little salt; mix thoroughly. Score the mixture into 4 equal portions and form them into patties slightly thinner at the center than the edges for even cooking and to ensure a flat surface (burgers plump as they cook). Drizzle the patties with EVOO. Cook the burgers, flipping once, 10 minutes for medium (adjust the timing for rarer or more-done burgers).
While the burgers cook, make the dressing: In a small bowl, combine the buttermilk, sour cream, ketchup, garlic, herbs and lemon juice; season with salt, pepper, and hot sauce to taste.
Place burgers on the roll bottoms and top with lettuce, onion rings and ranch dressing. Set the roll tops in place.
You may have to make a special request for course-ground beef at your butcher or supermarket meat counter.