This is a must try Burger!
Sauce
3 tbsp Mayo
2 tsp Dijon Mustard
2 tsp Relish or crushed pickles
1 tbsp sriracha
1 tbsp ketchup/Tomato sauce
Pinch salt
Boil potatoes in cold water for 30mins until you can poke a toothpick in like butter.
Squash potatoes with something that has a flat surface, shape them with your hands if they don't squash even.(be careful they will be hot)
Add some oil and salt then into the oven at 220C/430F for 30mins
Let them cool for a few mins before building your burger!