- 2 pounds medium sweet potatoes (about 4), peeled and cut into 1/2-inch wedges
- 3 tablespoons plus 1 teaspoon olive oil
- kosher salt and black pepper
- 1/2 small fennel bulb, cored and thinly sliced
- 1/2 small red onion, thinly sliced
- 3 tablespoons fresh lemon juice
- 1 1/4 pounds ground beef chuck
- 4 ounces Gouda, sliced
- 4 hamburger buns
- arugula, for serving
- Heat oven to 450° F. On a rimmed baking sheet, toss the potatoes, 2 tablespoons of the oil, ¾ teaspoon salt, and ¼ teaspoon pepper.
- Roast, tossing once, until golden brown and tender, 22 to 25 minutes.
- Meanwhile, in a medium bowl, toss the fennel, onion, lemon juice, 1 tablespoon of the oil, and ¼ teaspoon each salt and pepper. Set aside.
- Form the beef into four ½-inch-thick patties. Season with ½ teaspoon salt and ¼ teaspoon pepper. Heat the remaining teaspoon of oil in a large skillet over medium-high heat.
- Cook the patties for 3 to 4 minutes per side for medium-rare. During the last minute of cooking, top them with the cheese and cook, covered.
- Place the burgers on the buns with the fennel relish and arugula, if desired. Serve with the fries.