Cracklin' Cayenne Onion Strings
Slice onions very thin (almost shaved). Marinate in buttermilk for 1-2 hours. Combine flour and seasonings in a bowl. Heat oil to 325 degrees in heavy skillet or deep fryer. Toss one small handful of onions in flour mixture and drop into hot oil, separating with tongs (some sticking is fine; avoid allowing onions to form a ball). Fry just until golden and crisp, about 2 min. Remove and drain on paper towels. Repeat with remaining onions. Set aside.
Roughly mix cold beef and butter; shape into four patties. Salt and pepper exterior and grill to desired internal temp (125 degrees for medium rare, approx. 4 min per side on hot grill). Top each with two thin slices of cheddar for the last minute of cooking. Combine mayo and hot sauce; add 1 T mayo mixture to each toasted bun bottom. To assemble, add lettuce to dressed bun, then burger with cheese, peppers, avocado, onion strings, ketchup, mustard and, finally, toasted bun top. Serve immediately with a chilled Oregon beverage.