Berliner Burger
[Vegan]

To Make the Patties:

1. Place a large skillet over medium-high heat and add a drizzle of vegetable oil. Add the onion and fry for 5 to 7 minutes until soft and translucent. Add the garlic and mushrooms. Fry until the mushrooms shrivel and the excess moisture evaporates. Add the leek and fry for another minute. Transfer to a bowl and combine with the remaining patty ingredients.
2. Use a fork or your hands to make a sticky mixture, or pulse lightly in batches in the food processor. Taste and adjust the seasonings with salt and pepper if needed. Transfer the mixture to a bowl and refrigerate for 15 minutes, or up to 24 hours covered.
3. Divide the mixture into 4 equal portions and shape each into a patty. Place a skillet over medium-high heat and add a drizzle of vegetable oil. Fry the patties for 3 to 4 minutes per side. Lightly season with salt and pepper.
4. Assemble the patties in the toasted buns and top with mayonnaise, kraut, and Curry Ketchup.

For the Curry Ketchup:

1. Place a small saucepan over medium heat and add the oil.
2. Stir in the garam masala, tamarind paste, cumin, chili powder, and coconut sugar.
3. Cook for 1 minute, stirring. Stir in the ketchup until combined.
4. Let simmer for 1 minute. Remove from the heat and let cool. Transfer to a storage container and refrigerate.