In a large bowl, add 1 cup kidney beans + 4 cups water. Soak overnight.
Drain and transfer the beans to your pressure cooker (electric or stovetop). Add a pinch of salt + 1 cup of water.
For electric pressure cookers, cook for 22-25 minutes on MANUAL settings, High Pressure. For stovetop pressure cookers, cook for 5-6 whistles over medium heat. Do a quick release (we don't want the beans to become mushy).
Drain and transfer to a large bowl. Lightly mash them using a potato masher.
Add grated carrots + charred onions + salt + pepper + smoked paprika + onion powder + garlic powder. Mix them gently using your hands.
Add breadcrumbs and mix some more.
Scoop a handful (around 4-5 tablespoons) of the mixture and give them the shape of a burger patty. You can also use the lid of a container jar. Simply cover the inner of a lid with a plastic wrap and place a handful of the mixture in the lid. Gently press the mixture, remove/add more if needed, and then flip.
Transfer the patties to a baking sheet and let them chill for at least 2 hours.
Dipping in the slurry,
In a medium mixing bowl, add all-purpose flour + cornflour + 2/3 cup cold water. Mix well until smooth.
Dip the chilled patties and coat them on both sides.
Now place them in a bowl of breadcrumbs. Flip and coat on all sides.
Shallow-fry the patties until they're brown on both sides.
Layer and assemble the burger. I used vegan mayo + lettuce + tomatoes + patty + ketchup + onion in my recipe.
You can use canned kidney beans if you have one.
To prepare the charred onion, simply fry 1 sliced onion in 1 teaspoon of oil until they're dark. Stir frequently. You can also use lightly sauteed onions if you wish.