Our Smoked French Onion Soup starts with slowly caramelized onions, layered broths, a touch of wine, and plenty of melting cheese. Caramelizing the onions takes the longest, but the depth of flavor it adds makes it absolutely worth the wait.
Pellet Grill French Onion Soup Recipe
Using a cast-iron pan, a pile of sweet onions, a little olive oil, and a few hours on a pellet grill yields an incredibly rich and smoky base for French onion soup. The smoking adds a subtle, savory layer to the caramelized onions that elevates the whole bowl.
This recipe is easier than it seems: most of the work is passive, while the onions slowly turn sweet and golden. If you can be home and stir every 30–45 minutes, the process is straightforward.
Once the onions are ready, assembling the soup is quick and forgiving. The final step—topping with toasted bread and melted cheese—is what makes it comforting and dramatic.
Recipe Shopping List
Here are the ingredients you’ll need to make this smoked French onion soup. Scroll down to the instructions for full details on quantities and timing.
- Sweet onions (yellow or a mix of varieties)
- Olive oil
- Salt and freshly ground black pepper
- Fresh garlic (smoked garlic works wonderfully)
- Fresh or dried thyme
- Beef broth (good quality)
- Chicken broth (good quality)
- Red wine (robust and drinkable)
- White wine (dry, drinkable)
- Smoked provolone or another melting cheese
- French bread or crusty baguette, sliced and toasted
This soup rewards patience and quality ingredients, so choose broths and wines you enjoy drinking. Avoid using powdered bouillon if you can—the better the base, the better the result.
How To Make This Recipe
Below is an overview of the process. When you cook, follow the detailed steps and timings in the instructions section. You can also caramelize the onions a day ahead and finish the soup the next day for convenience.
- Smoke and caramelize the onions – Slice the onions thinly and place them in a large cast-iron skillet with olive oil. Preheat your pellet grill to a low temperature (around 225–275°F is ideal). Let the onions cook slowly, stirring every 30–45 minutes, until they are deeply golden and sweet. This can take several hours depending on temperature and volume.
- Build the soup – Transfer the caramelized onions to a stockpot. Add beef and chicken broths, both wines, smashed garlic, and thyme. Bring to a gentle simmer, then cook slowly to marry flavors for about an hour. Taste and adjust seasoning with salt and pepper.
- Toast and melt – Lightly toast slices of French bread. Ladle the hot soup into oven-safe bowls, place a toast round on top, and add slices of smoked provolone. Broil briefly until the cheese is melted, golden, and bubbling. Take care—broilers work fast.
Try it with fresh homemade French bread for the best experience.
Recipe Tips
French onion soup is deceptively simple, but small choices make a big difference. Pay attention to the onions, the broths, and the wines—those elements define the final flavor. Below are practical tips to help you get the best outcome.
Use plenty of onions and plenty of patience
Double the quantity of onions you think you need. Slow, patient caramelization transforms raw onion into sweet, savory goodness. If you end up with extra caramelized onions, store them in an airtight container in the fridge—they are fantastic on burgers, sandwiches, crostini, or mixed into compound butter.
Better bases make better soup
Choose high-quality boxed broths or homemade stock instead of powdered mixes. For wine, pick a dry white (Chardonnay or Pinot Grigio) and a full-bodied red (Cabernet or Pinot Noir) that you would be comfortable sipping. The wine flavors should complement the soup without being floral or overly sweet.
Recipe FAQ
What kind of onions are best for French onion soup?
Sweet yellow onions are a top choice for their natural sugar and caramelization potential. You can also mix varieties—red, yellow, and even some shallots—to add nuance and depth.
What is the best way to store leftover French onion soup?
Keep the bread separate from leftover soup to avoid sogginess. Store soup in an airtight container in the refrigerator for up to 3–4 days. Reheat gently on the stovetop or in the microwave until piping hot.
How do you reheat leftover French onion soup?
Reheat the soup until steaming hot, then add toasted bread and cheese and broil briefly to re-melt the cheese. If using the oven, place oven-safe bowls on a sheet and watch carefully while broiling—the cheese can brown quickly.
More Recipes
- Stovetop French Onion Soup
- French Onion French Dip Sandwich
- Traeger Smoked Caramelized Onions
- Smoked Caramelized Onion Butter
- How To Caramelize Onions
Smoked French Onion Soup
Yield: 6 servings
Hearty French onion soup made with onions smoked on a pellet grill for a rich broth topped with toasted bread and melted smoked provolone.
Prep Time: 10 minutes
Active Cook Time: 1 hour
Onion Time (caramelizing): 3 hours (approx.)
Total Time: ~4 hours 10 minutes
Ingredients
- 4 large sweet onions, thinly sliced
- 4 tablespoons olive oil
- 4 cups chicken broth
- 4 cups beef broth
- 3/4 cup white wine (dry)
- 3/4 cup red wine (robust)
- 2 cloves garlic, smashed
- 1/4 teaspoon ground thyme (or 1 teaspoon fresh)
- 12 slices smoked provolone
- 12 slices toasted French bread
- Salt and freshly ground black pepper, to taste
Instructions
- Preheat your pellet grill or smoker to 275°F. In a large cast-iron skillet combine the sliced onions and olive oil. Spread them evenly and let them cook, stirring occasionally, until golden brown and very soft. At low temperature this can take 3–5 hours. If you want to speed up, raise heat to 325°F and watch closely—caramelization will occur faster but requires careful stirring.
- Transfer the caramelized onions to a large stockpot. Add chicken and beef broths, both wines, garlic, and thyme. Bring to a gentle simmer. Taste and adjust seasoning with salt and pepper based on the strength of your broths and wines.
- Let the soup simmer over medium-low heat for about an hour to meld flavors.
- Preheat your oven broiler. Lightly toast the French bread slices. Place oven-safe bowls on a baking sheet, ladle hot soup into each bowl, top with a toasted bread round and two slices of smoked provolone.
- Broil the assembled bowls until the cheese is melted, bubbly, and slightly browned, about 1–3 minutes depending on your broiler. Watch closely to prevent burning.
- Remove carefully and serve hot. Bowls will be very hot—use oven mitts.
Nutrition (per serving, estimate)
Calories: 799 | Total Fat: 28g | Saturated Fat: 16g | Cholesterol: 67mg | Sodium: 2659mg | Carbohydrates: 93g | Fiber: 6g | Sugar: 17g | Protein: 35g
Nutrition data is an estimate and will vary based on exact ingredients and portions.