Why This Recipe Works: Grinding your own turkey for burgers reaps big rewards when using collagen-rich turkey thighs. To ensure a silky texture and to help the burgers retain moisture, we made a paste with a portion of the ground turkey plus gelatin, soy sauce, and baking soda; mushrooms provided meaty flavor and texture.
If you are unable to find boneless, skinless turkey thighs, substitute one 2-pound bone-in thigh, skin and bones removed, trimmed. To double this recipe, spread turkey over two baking sheets in step 1 and pulse in food processor in six batches.
1 1/2 pounds boneless, skinless turkey thighs, trimmed and cut into 1/2-inch pieces
1 tablespoon unflavored gelatin
3 tablespoons chicken broth
6 ounces white mushrooms, trimmed
1 tablespoon soy sauce
Pinch baking soda
2 tablespoons plus 2 teaspoons vegetable oil, divided
1/2 teaspoon table salt
1/4 teaspoon pepper
4 slices cheese (4 ounces) (optional)
4 hamburger buns, toasted if desired
For the burger blend: Arrange turkey in single layer on rimmed baking sheet and freeze until very firm and starting to harden around edges but still pliable, 35 to 45 minutes.
Sprinkle gelatin over broth in small bowl and let sit until gelatin softens, about 5 minutes. Pulse mushrooms in food processor until coarsely chopped, about 7 pulses, stopping and redistributing mushrooms as needed; transfer to bowl.
Working in three batches, pulse turkey in now-empty processor until ground into 1/8-inch pieces, about 20 pulses, stopping to redistribute meat as needed; transfer to separate large bowl.
Return 1/2 cup (about 3 ounces) ground turkey to again-empty processor along with softened gelatin, soy sauce, and baking soda. Process until smooth, about 2 minutes, scraping down sides of bowl as needed. With processor running, slowly add 2 tablespoons oil until incorporated, about 10 seconds. Return mushrooms to processor with paste and pulse to combine, 3 to 5 pulses. Transfer mushroom mixture to bowl with turkey and knead with your hands until combined.
To Shape Patties
With lightly greased hands, divide turkey mixture into four lightly packed balls, then gently flatten into 3/4-inch-thick patties. Using your fingertips, press center of each patty down until about 1/2 inch thick, creating slight divot. Cover and refrigerate until ready to cook. (Patties can be refrigerated for up to 1 hour or frozen for up to 2 weeks. To freeze, stack patties, separated by parchment paper, wrap in plastic wrap, and place in zipper-lock freezer bag.)
To Cook Burgers
For a skillet: Adjust oven rack to middle position and heat oven to 300 degrees. Season patties with salt and pepper. (If previously frozen, thaw at room temperature for 30 minutes before seasoning and increase baking time to 12 to 14 minutes.) Heat remaining 2 teaspoons oil in 12-inch nonstick skillet over high heat until just smoking. Using spatula, transfer patties to skillet, divot side up, and cook until well browned on first side, 2 to 4 minutes. Flip patties and cook until well browned on second side, 2 to 4 minutes. Transfer patties to rimmed baking sheet, divot side down, top with cheese, if using, and bake until burgers register 160 degrees, 6 to 10 minutes. Transfer burgers to platter and let rest for 5 minutes. Serve burgers on buns.
For a charcoal grill: Freeze patties for 30 minutes. (If previously frozen, do not thaw.) Open bottom vent completely. Light large chimney starter filled with charcoal briquettes (6 quarts). When top coals are partially covered with ash, pour evenly over half of grill. Set cooking grate in place, cover, and open lid vent completely. Heat grill until hot, about 5 minutes. Clean and oil cooking grate. Brush one side of patties with 1 teaspoon oil and season with salt and pepper. Using spatula, gently flip patties, brush with remaining 1 teaspoon oil, and season second side. Place burgers, divot side up, over hotter part of grill and cook until well browned on first side and meat easily releases from grill, 5 to 7 minutes. Flip, top with cheese, if using, and cook until well browned on second side and meat registers 160 degrees, 5 to 7 minutes. Transfer burgers to platter and let rest for 5 minutes. Serve on buns.
For a gas grill: Freeze patties for 30 minutes. (If previously frozen, do not thaw.) Turn all burners to high, cover, and heat grill until hot, about 15 minutes. Leave primary burner on high and turn off other burner(s). Clean and oil cooking grate. Brush one side of patties with 1 teaspoon oil and season with salt and pepper. Using spatula, flip patties, brush with remaining 1 teaspoon oil, and season second side. Place burgers, divot side up, over hotter part of grill and cook, covered, until well browned and meat easily releases from grill, 5 to 7 minutes. Flip, top with cheese, if using, and cook until well browned on second side and meat registers 160 degrees, 5 to 7 minutes. Transfer burgers to platter and let rest for 5 minutes. Serve on buns.