For Fresno chilies, roast over open flame until skin blackens. Seal in plastic bag and cool, 10 min. Remove skins under cold water and discard stems and seeds. Slice thinly into strips and reserve.
Combine Sriracha Mayo ingredients in small bowl and chill until ready to serve.
Preheat oven to 350 degrees and bake bacon on a sheet pan for 18-20 min. Drain on paper towels and set aside.
Preheat grill or large cast iron skillet to medium-high heat. Working quickly, gently shape four, cold ground beef patties; season generously with salt and pepper. Cook 3 min per side for medium-rare to medium doneness. Add cheese for final minute of cooking time, covering until just melted. Toast or grill buns until lightly browned. Build burgers on buns, topping with bacon, kimchi, roasted chilies (optional), lettuce, onion, tomato and Sriracha Mayo. Serve with Sweet Potato Fries and remaining Sriracha Mayo.
Tips for a great burger:
- Use freshly ground beef with at least 15% fat content (up to 30%). This adds much needed moisture and flavor.
- Season the exterior of burgers with salt and pepper just before cooking. Seasoning too long before cooking or seasoning before shaping will draw out the juices.
- Always work with cold ground beef and shape the patties quickly, being careful not to overwork. The heat from your hands can melt the fat, and too much pressure can change the texture dramatically, making a juicy, tender burger a dry, tough puck.
- Make a small depression in the center of the patties with your thumb to cook burgers evenly and keep them from shrinking.
- Cooking in a cast iron skillet or griddle is ideal, since a grill allows all of the juices and fat to drip away. Three minutes per side for a 1/3 lb burger at a moderately high heat produces a medium-rare to medium burger.
- If using a skillet, add a small drizzle of oil or butter to the pan before adding burgers to kick-start the cooking process.