Peel and cube the potatoes and place them in a large pot. Cover with cold salted water. Bring to a boil and cook until potatoes are fork tender, about 35–45 minutes. Drain.

Mash potatoes with a potato ricer or masher.  Add in mayonnaise and season with salt and pepper as necessary. Set aside.

In a saucepan over medium heat, heat one tablespoon of oil. Sauté onions until caramelized, about 45 minutes. Season with salt and pepper.

In a large bowl, combine flour, salt, sugar, eggs, soy milk, and 1/4 cup oil. Mix well to form a soft dough. Turn onto plastic wrap and allow to rest for 10 minutes.

Preheat oven to 350 degrees Fahrenheit.

Turn the dough onto a floured surface. Cut into 12 pieces for large knishes, or 18 pieces for smaller knishes. Roll each piece into a circle.

Place one teaspoon of caramelized onion and about two tablespoons of potato mixture in the middle of the circle. Pleat the top to close and place onto a baking sheet covered with Gefen Parchment Paper. Brush the tops with beaten egg and bake for 35–40 minutes, or until golden brown.

Preheat oven to 250 degrees Fahrenheit.

Lay sliced onion in a 9- x 13-inch (20- x 30-centimeter) baking pan and place brisket on top. Sprinkle with onion and garlic powders, then pour meat sauce on top. Pour the water into the side of the pan and cover tightly. Bake for five to six hours or until very soft.

Shred with two forks.

Place your knishes on a platter or on individual plates. Top with pulled brisket and enjoy!