Coat the bottom of a large cast iron skillet with grapeseed oil and place it over medium-high heat. Add the onions and cook, stirring a bit, until they are brown and crispy, about 5 minutes. Season them to taste with salt and pepper. Set the onions aside and do not wash the pan.
For the burgers
In a small bowl, use a whisk or a fork to combine the Sriracha, soy sauce, honey, garlic, ginger, and salt. Add the beef to a large mixing bowl and pour in the Sriracha mixture. Use your hands or a large spoon, to mix everything together. Only mix until it's combined.
Shape the meat into 4 evenly sized burgers.
Heat the same pan where you cooked the onions, and add a little more grapeseed oil. When the pan is very hot, add the burgers. You should hear a sizzling sound — if you don’t, wait! You won’t get a nice “crust” on the burger if it’s not hot enough. Cook for about 4 minutes, then flip the burgers over and reduce the heat to medium-low. For medium rare, cook for about another 5 minutes or until the desired doneness. Place the cooked burgers on a plate and cover with foil.
For the Lime Aioli
Mix all of the ingredients together in a small mixing bowl. Set aside in the refrigerator.
To serve, set up a burger bar. Put the burgers and burger buns on platters. (Toast the buns if you'd like.) Arrange the lettuce, avocado and tomato slices on another platter. Spoon the Lime Aioli into a small bowl and put the onions in another. Add serving utelsils and the bar is set up.