Bring 1 cup water to a boil, add a bouillon cube, cover and remove from heat
Spread the mayo on one side of each bread slice
In a medium skillet cook half the onions until translucent- about 5 minutes
While the onions cook lightly break the meat into a mixing bowl, then lightly break in the remaining half of the bouillon and the remaining onions.
Lightly form the meat into a ball in your hands and set aside
When the onions are cooked add the broth to the pan and bring to a boil, then reduce heat to medium
place the patty in the center of the broth and press it flat enough that the broth raises to about half way up. If you don't have a press, form the patty with your hands to be about 1/2" thick
Poach the burger in the beef broth for 2 minutes per side.
While the burger poaches, heat a large skillet on medium-high, then place the bread mayo down and add a slice of cheese to each. Toast the bread to almost desired doneness. If you time this right you can transfer the patty directly to the bun, top with onions from the broth
top with dijon, add the top bread piece, cut in half (diagonally!) and serve with a pickle