Cook potato in boiling water until very soft, about 15 minutes. Drain and cool slightly.

Cook cauliflower in boiling water until very soft, about 6 minutes.

Drain and cool slightly.

Preheat the oven to 400°F.

Place cashews in a food processor and pulse until finely ground.

In a large bowl, combine potato, cauliflower, cashews and remaining ingredients.

Use your hands to break up chunks of potato and cauliflower, and press the ingredients until they hold together.

With damp hands, form into patties* about 4 inches in diameter and 3/4-inch thick.

Place on a parchment paper-lined baking sheet.

Bake 15 minutes, then flip burgers and continue to bake until lightly browned on the other side, about 15 minutes longer.

*Forming neat veggie burgers: 
Dampen the inside of a 1/2-cup measuring cup and pack it with the burger mixture, pressing down firmly. Turn the cup over and shake it gently to release the mixture into the palm of your hand, then press down with your other hand until the patty is about 3/4-inch thick.

Freezing veggie burgers:
Cool cooked burgers and wrap individually in plastic wrap and then foil, or place them in individual resealable plastic bags, and freeze up to 6 months. To reheat, unwrap the burgers, place on a parchment paper-lined baking sheet and bake at 300°F until heated through, 20 to 25 minutes.