Step 1

Heat 1 Tbsp of olive oil in a large skillet, on Medium-High heat.

Step 2

Add the diced onions and salt, and give it a good stir.

Step 3

Reduce heat to medium/low. Cook, stirring occasionally, 15-20 minutes, or until onions are lightly browned.

Step 4

Turn heat back up to Medium-High. Add 1 Tbps water, stir and let cook about 2-3 minutes until water evaporates (or until onions start to slightly stick to the pan).

Step 5

Repeat 2 more times.

Step 6

Store in a container until ready to use.

Step 7

Add all ingredients for the special sauce in a bowl. Whisk until well combined. Cover, and store in the refrigerator until ready to use.

Step 8

Heat a skillet on Medium-High heat , add a little butter, about 1 tsp per bun. Toast the inside of the buns for about 1 minute, until the edges are dark brown (but not burned). Set aside.

Step 9

Cut the beef into 8 pieces, and roll each piece into a ball.

Step 10

Lay out a large piece of wax paper.

Step 11

Flatten out a beef ball in your hands, lay on the wax paper and start shaping into a patty. You want it really thin, about 4” diameter, or slightly larger then the bun.

Step 12

Repeat, until you have all beef patties laid out on your wax paper. Season them with salt and pepper.

Step 13

Cut a square shape around each beef patty, then stack them on a plate.

Step 14

Lightly oil a large skillet and heat on Medium-High for a few minutes (you want the pan hot before adding the patties).

Step 15

Place 2 patties on the pan (seasoned side down), then quickly season the top with salt, pepper and 1 Tbsp mustard.

Step 16

Cook until browned, about 2-3 minutes. Flip, then cook 1 minute.

Step 17

Add sliced cheese on both patties.

Step 18

Add 1 heaping Tbsp of caramelized onions on one patty, and stack the other patty on top. Remove the stack from the pan.

Step 19

Repeat with the remaining patties.

Step 20

Assemble the burgers in this order:-bottom bun-1 heaping Tbsp sauce-4 pickle slices-1 tomato slice-2 lettuce leaves, torn-double meat double cheese onion stack-top bun

Step 21

All done! :)