Caramelized Onion Mushroom Swiss Turkey Burger

Key Ingredients and Substitutions

Burgers are no longer just fast food, and the investment you make in preparation time and ingredients will determine how memorable your creations are. None of the ingredients are especially expensive, so you might as well buy the best you can find. Turkey by itself can be somewhat bland and dry, so skipping the herbs and spices is not recommended. Feel free to experiment with some of your own favorite sauces and spices to tailor the flavor to your own personal tastes.

The full ingredient list and measurements are listed in the printable recipe below.

• Turkey. There is some variation in the quality and price of ground turkey, but even the best isn’t all that expensive. Deciding the best lean-to-fat ratio may be your biggest conundrum, especially if you are health-focused. While you can purchase 99% lean ground turkey, we really recommend something in the 80-85% range so your burgers don’t come out too dry and flavorless.
• Caramelized Onions. This is a simple caramelized onion recipe that requires an investment in patience to yield the best results. It doesn’t take much longer to make a double or triple batch, and they freeze and reheat very well. Starting from scratch will more than double the preparation time, so do your future self a favor and make some extra if this is your first time.
• Mushroom. We used Cremini (or Baby Bellas) for this recipe, but any mushroom would work including the white buttons found at any supermarket. If you really want to raise the bar for this burger, try some Shiitake, Oyster, or Chanterelles – all of them are umami bombs that elevate this burger to the next level.
• Swiss Cheese. We just used pre-sliced deli swiss cheese which made preparation easy. If you really love this ingredient though, buying some Emmenthaler or Gruyère can only enhance the flavors of the onions and mushrooms.

How to Make Caramelized Onion Mushroom Swiss Turkey Burger

Here are the quick step-by-step instructions with visuals; you can find the full instructions with the exact ingredients in the recipe card below.
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Pro-tip: Caramelized onions can be made in advance and frozen for future use so make a big batch and then freeze it in a freezer-safe container.

1. Caramelize the Onions: Roughly chop the onions so that slices are between ⅛ and ¼ inches thick. Heat the butter and olive oil in a saucepan on medium heat. Once the butter has melted, add onions and sweat them until they become translucent. Reduce heat to low and continue to cook onions, stirring every 5-10 minutes to prevent them from sticking. Deglaze the pan with a tablespoon or two of water or chicken stock when fond starts to form on the pan. As onions continue to caramelize, continue stirring every 5-10 minutes and deglazing the saucepan as fond forms and the onions are no longer loose in the pan. When the onions achieve a deep golden brown (or dark brown) remove them from heat and set aside.

2. Sauté the Mushrooms: In a cast-iron skillet over medium heat, heat the olive oil and butter. Add mushrooms and sauté until they have released their water,  approximately 2-3 minutes. Remove mushrooms from skillet and set aside.

3. Prepare the Burger Patties: In a large bowl mix together ground turkey with Worcestershire sauce, kosher salt, black pepper, panko breadcrumbs, garlic salt, onion powder, and chopped fresh parsley. Divide the turkey mixture into three equal portions and form them into patties. Place patties on a small baking sheet and refrigerate for 10-15 minutes. Note: This step can be done in advance just keep the burger patties refrigerated until ready to cook.

4. Cook the burger: In the same cast-iron skillet used to sautéed the mushrooms, cook turkey patties for approximately 3-5 minutes per side then cover with a lid to help cook the center all the way through. When burgers have reached an internal temperature of 165 degrees top with cheese and cover until cheese has melted.

5. Plate: Serve burgers on a toasted bun and top with sautéed mushrooms and caramelized onions.  Add additional toppings if desired.

Recipe Pro-Tips and Notes

• Use a preheated cast-iron or nonstick skillet to get a browned seared exterior.
• Turkey burgers can also be grilled on an outside gas or charcoal grill for added flavor.
• Turkey burgers need to be cooked to an internal temperature of 165 degrees. Above 165 degrees and burgers will begin to dry out.
• To bind the patties together use breadcrumbs. It will also help the patties keep their shape.
• Turkey burgers are best served immediately when they are still juicy.

Make-Ahead and Storage

Make-Ahead: Make the turkey burgers through step 2 of the recipe (prior to cooking). Place them on a baking sheet and cover them with plastic wrap. Refrigerate up to one day prior to cooking. The onions and mushrooms can also be cooked in advance and then refrigerated in an air-tight container.

How to Store: For cooked burgers, allow them to cool completely then tightly wrap individual burgers with plastic wrap, aluminum foil, or food-safe storage containers to prevent drying and airflow. Cooked turkey burgers can be stored safely in the refrigerator for up to 3-4 days or frozen for up to 3 months. For uncooked burgers, make the turkey burgers through step 2 of the recipe then place burgers on a parchment-lined baking sheet and put them in the freezer for one hour. Once the patties have partially frozen, layer them between parchment paper in a freezer bag or freezer-safe container. Freeze burgers for up to 3 months. To cook, thaw burgers overnight in the refrigerator and then cook as recommended in step 3 of the recipe.

How to Reheat: Leftover burgers that have been cooked can be reheated in the oven, stovetop, or microwave. Avoid partial reheating, which can create a breeding ground for bacteria.

• Oven Reheating: Preheat the oven to 350°F. Place burgers on a baking sheet and reheat for 7-10 minutes, flipping halfway through. Check internal temperature with a food thermometer; it should reach 165°F. Add the Swiss cheese, do so in the last 1-2 minutes.
• Stovetop: Heat a skillet over medium heat. Add a little oil or butter if needed and place burgers in the pan then cook for 3-5 minutes per side, until heated through and browned. Check internal temperature with a food thermometer; it should reach 165°F.
• Microwave: Place burgers on a microwave-safe plate with a splash of water or broth to add moisture. Cover loosely with a microwave-safe lid or plastic wrap and heat on medium power for 1-2 minutes per patty, flipping halfway through. Check internal temperature with a food thermometer; it should reach 165°F.

Frequently Asked Questions