Combine plant-based meat product and 1 tablespoon burger seasoning in medium bowl; let stand at room temperature for 5 minutes. Stir together ketchup and remaining 1 teaspoon burger seasoning in small bowl; set aside.

Form plant-based mixture into two 4-inch round patties. Lightly brush a grill pan with oil; heat over medium-high heat. Cook patties 8 to 10 minutes or until 165°, turning halfway through.

To assemble sandwiches, spread 2 tablespoons ketchup mixture on each bun bottom. Top each with lettuce, burger, and other desired add-ons. Spread mayo on bun tops, if desired, and place on top to enclose sandwiches.