Preheat oven to 450 degrees.
Using a mandoline or sharp chef’s knife, thinly slice cucumber and radishes. In a small bowl, combine the vinegar, sugar and 1/4 teaspoon salt, stirring until the sugar and salt are dissolved. Add the cucumber and cilantro and toss to combine. Let sit, tossing occasionally, for at least 15 minutes and up to 6 hours.
Place veggie burgers on a baking sheet. Bake in the oven for 4-5 minutes on each side.
Toast buns and assemble your veggie burgers with quick pickles, a lettuce leaf, a tomato slice and your favorite burger accompaniments.