Prepare the Mushrooms

Heat your oven to 400°F.

Warm about a tablespoon of olive oil in a large oven-safe skillet over medium-high heat. Add the mushrooms and let them brown well. Don’t add salt—this helps them sear instead of steam. Once they’re golden, set them aside.

Brown the Sausages

Add another splash of oil if needed.

Place the sausage slices in the skillet and lightly brown both sides. This only takes a couple of minutes. Move them to the bowl with the mushrooms.

Build the Flavor Base

Add the last bit of olive oil if the skillet looks dry.

Lower the heat to medium and cook the onion until softened. Stir in the celery, carrots, and garlic.

Pour in the apple cider to deglaze the skillet, using your spoon to loosen any browned bits stuck to the bottom. Let the liquid simmer until it reduces.

Create the Stew

Stir in the tomato paste, sun-dried tomatoes, Worcestershire, soy sauce, brown sugar, thyme, and optional spices.

Add the diced tomatoes and kidney beans.

Mix well and bring the pot back to a simmer.

Return the browned mushrooms and sausage slices to the skillet and let everything bubble gently for about 5 minutes so the flavors come together.

Thicken the Gravy

Whisk the flour with the cold water until completely smooth.

While the stew is simmering, drizzle the flour mixture into the center of the skillet, whisking constantly.

As it cooks, the broth will thicken into a hearty, stew-like consistency.

Taste and adjust seasoning.

Add the Potato Layer

Toss the sliced potatoes in olive oil.

Arrange the slices over the top of the stew, overlapping them slightly so they form a decorative “roof.”

Sprinkle with a little coarse salt.

Transfer the skillet to the oven and bake for 25–30 minutes, or until the potatoes are tender and starting to crisp at the edges.