For the bowls:

1. Place the beef in a medium bowl and create a small round well in the center of the beef. Salt and pepper the beef, grate about 1/4 of an onion into the well, and also pour the heavy cream into the well. Using your hands, gently mix all the ingredients until they are well combined. Don’t over-mix or the meat will become tough when cooking.
2. Preheat a large skillet over medium-high heat until very hot. Form the beef into a flat round roughly the size of the frying pan you are using. I like to use a well-seasoned cast-iron skillet so that you get a great sear on each side of the beef before breaking it apart. Cook on one side until there is a nice crispy layer. Carefully turn the meat over and sear the second side. Searing helps lock in all the juices that keep the meat moist and tender. Using a spatula, break apart the meat into small chunks and keep cooking until there is no more pink meat. Remove from heat and set aside. Drain the beef, or using a slotted spoon, transfer the beef to a clean bowl. Discard the excess grease.
3. While the beef is cooking, chop the lettuce and slice the vegetables you’ll be using, and place them in individual bowls.  
4. Start by adding the chopped lettuce to each serving bowl. Place the beef on top of one side of the lettuce and arrange the vegetables and cheese around the meat. Add a small cup of sauce to each bowl, serve, and enjoy!

For the sauce:

1. Finely chop the cornichons and set aside.
2. In a small bowl, add the mayo, ketchup, Worcestershire sauce, and sriracha sauce and whisk until combined. Add the cornichons and stir again. 
3. Transfer the sauce to four small cups for serving in the burger bowls.