Mushroom Omelet Recipe

Parboil (optional for tender interior)

Place the potato cubes in a pot of cold salted water. Bring to a boil and simmer 5 minutes until just tender but still holding shape. Drain and dry thoroughly on a clean kitchen towel or paper towels.

Heat a large skillet over medium-high heat. Add the beef tallow and let it melt and shimmer. Add the dried potato cubes in a single layer (work in batches if necessary) and cook without stirring for 3–4 minutes to develop a brown crust.

Stir and continue to fry, turning occasionally, until all sides are golden brown and potatoes are cooked through, about 8–10 more minutes total. Reduce heat if they brown too quickly.

Season with 3/4 tsp salt and 1/4 tsp black pepper, toss with chopped parsley if using. Keep warm while making the omelet (transfer to a low oven at 200°F / 95°C if desired).

Heat a medium skillet over medium heat. Add 1 tsp olive oil and 1 tbsp butter. Once butter foams, add the minced shallot and sauté 30–45 seconds until softened.

Add the sliced mushrooms in a single layer as much as possible and let sear without stirring for 1–2 minutes to develop color. Stir and continue cooking 3–4 minutes until mushrooms release their moisture and begin to brown.

Add 1/2 tsp minced garlic, 1/2 tsp thyme leaves, 1/2 tsp salt and 1/4 tsp black pepper. Cook another 1–2 minutes until fragrant and most moisture has evaporated. Taste and adjust seasoning. Remove from heat and keep warm.

In a bowl, crack 3 eggs. Add 2 tablespoons milk, 1 tsp salt and 1/4 tsp black pepper. Whisk vigorously until homogenous and slightly frothy.

Heat a 8–10 inch nonstick or well-seasoned omelet pan over medium-low heat. Add 1 tbsp butter and swirl to coat; reduce heat to low so butter remains foamy but not browned.

Pour the beaten eggs into the pan and let sit undisturbed for 10–15 seconds to set at the edges. Using a spatula, gently pull the cooked edges toward the center while tilting the pan so uncooked egg flows to the edges. Repeat until the surface is mostly set but top still slightly moist, about 1–2 minutes total.

Sprinkle half of the scallion slices evenly over the omelet surface. Spoon the warm mushroom filling down the center in a line. Scatter 1/2 cup grated Gruyère over the mushrooms.

Fold one third of the omelet over the filling with a spatula, then fold the opposite side over to form a tri-fold (or fold in half if you prefer). Let cook 20–30 seconds more to melt the cheese through, keeping heat low to avoid overbrowning.

Slide the omelet gently onto a plate, seam side down. Garnish with remaining scallion slices and a small pat of butter or 1/2 tsp tallow melted on top if desired.