Preheat the oven to 400 degrees and line 2 baking sheets with foil or use nonstick baking sheets. Thoroughly rinse produce. Cut tomato into 1/4" rounds. Cut sweet potato 1/4" wedges. Peel red onion and cut into thin rounds.

Place sweet potato wedges in a mixing bowl. Add 1 Tbsp. olive oil and a pinch of salt and pepper. Mix well with hands or a spatula to ensure wedges are evenly coated. Place wedges on one of the prepared baking sheets and place on the middle rack of the oven to roast for 20-25 minutes, or until golden brown and lightly crisped. Remove from oven and allow to cool slightly on the uncovered baking sheet before serving. (This will help the fries get and stay crispy.)

While sweet potatoes are cooking, bring a small pot with apple cider vinegar, 1 cup water, sugar, and 1 Tbsp. salt to a boil. When boiling, add red onions and let boil for 1 minute. Remove pot from heat and let steep for 5 minutes. A few ice cubes will help cool the pickled onions quickly. Drain and set aside. This technique is called “flash pickling,” and it’s an easy way to lend slow-pickled flavor in a flash!

Shape turkey into 2 equal patties. Add salt and pepper to each side. Heat 2 tsp. olive oil in a medium pan over medium-high heat. Once hot, add patties and cook until a nice brown sear forms, about 3-4 minutes per side. Transfer patties on the second prepared baking sheet and cook on top rack of oven for 4-5 minutes or until burgers reach a minimum internal temp of 165 degrees. Top with cheese slices and return to oven to bake for 1 minute, or until cheese is melted.

If desired, toast or warm pretzel buns in oven while burgers are cooking. Place turkey burger on bottom half of bun. Top with baby arugula, tomato, and pickled onions, plus other half of bun. Arrange sweet potato wedges on the side.