Plant-Based Smashed Burgers

Heat 2 tablespoons oil in a large cast-iron skillet over medium heat. Add onions and cook, stirring occasionally, until caramelized, 15 to 20 minutes. Add vinegar, brown sugar, thyme, 1/4 teaspoon pepper and 1/8 teaspoon salt. Cook, stirring, until most of the liquid has evaporated and the mixture is slightly syrupy, about 2 minutes. Transfer the mixture to a medium bowl. Wipe out the pan.

Meanwhile, combine ground "meat," chili powder and the remaining 1/4 teaspoon pepper and 1/8 teaspoon salt in a large bowl. Form into 4 patties and smash to about 1/4 inch thick.

Heat the remaining 1 tablespoon oil in the pan over medium-high heat. Add the patties and cook until browned on both sides, 3 to 4 minutes.

Serve the burgers on toast with the onion relish, arugula and tomato.