French Dip Recipe

Cook onions slowly

Heat 1 tbsp olive oil and 1 tbsp butter in a large skillet over medium-low heat until butter melts. Add the thinly sliced onions, 1/4 tsp salt and 1/2 tsp sugar. Stir to coat and spread in an even layer.

Cook onions, stirring every 5–7 minutes, adjusting heat so they soften and brown slowly without burning. Total cooking time ~25–30 minutes until deep golden and jammy.

In the last 2 minutes, add 1 tsp balsamic vinegar to deglaze and bring out sweetness. Remove from heat and set aside.

In a medium saucepan, combine 3 cups beef au jus or low-sodium beef broth and 1 tbsp beef base (or demi-glace). Bring to a gentle simmer over medium heat.

Add 1 tsp minced garlic, 1 tsp fresh thyme (or 1/2 tsp dried), 1/4 tsp black pepper and 1/4 cup red wine (optional). Simmer gently 8–10 minutes to meld flavors. Taste and adjust seasoning; keep warm on very low heat until serving.

Oven-baked fries (recommended)

Preheat oven to 425°F (220°C). Toss 3 cups cut russet potatoes with 2 tbsp olive oil, 1 tsp salt, 1/4 tsp black pepper and 1/2 tsp paprika (optional). Arrange in a single layer on a baking sheet lined with parchment.

Bake 25–30 minutes, flipping halfway, until golden and crisp. Keep warm or season again with a pinch of salt right after coming out of the oven.

Or deep-fry

Heat vegetable oil in a deep pot to 350°F (175°C). Fry potatoes in batches 3–5 minutes until golden and crisp. Drain on paper towels and season with salt and pepper.

If prime rib is refrigerated, slice thinly (if not pre-sliced) and place in a shallow oven-safe dish. Season lightly with 1 tsp salt and 1/2 tsp black pepper distributed over the meat.

Preheat oven to 375°F (190°C). Add 1/4 cup of the prepared au jus to the bottom of the dish with the sliced prime rib to keep it moist. Cover loosely with foil and warm for 8–10 minutes, until heated through but not overcooked.

Meanwhile, split the 4 ciabatta hoagie rolls lengthwise (but not all the way through if you prefer a hinge). Lightly butter the cut faces with the reserved 2 tbsp unsalted butter.

Toast the buttered rolls on a baking sheet in the oven for 5–7 minutes until golden and crisp at the edges. Alternatively, toast on a skillet over medium heat until browned.

Once prime rib is warmed, remove foil and place sliced meat on the bottom half of each roll, dividing evenly. Top meat with a generous portion of caramelized onions.

Place two slices of Swiss cheese over the onions/meat on each sandwich. Return open sandwiches to the oven for 2–3 minutes or under a broiler briefly (watch closely) until cheese is melted.

Close sandwiches, press gently, and cut in half if desired. Spoon a few tablespoons of warm au jus into small serving bowls for dipping alongside each plate. Garnish fries with chopped parsley if using.