SCALLOPED POTATOES AND MUSHROOMS
Serves: 8
1 tbsp (15 mL) olive oil, plus more for the baking dish 1 large yellow or white onion, thinly sliced (about 2 cups/ 500 mL) 1 red bell pepper, seeded and finely chopped (about 1 1/2 cups/375 mL) 1 lb (454 g) button or cremini mushrooms, trimmed and sliced ( heaping 4 cups/1 L) 1/4 tsp (1 mL) dried thyme 1 1/2 tsp (7.5 mL) kosher salt 1/2 tsp (2.5 mL) freshly ground black pepper 3 lb (1.4 kg) Yukon gold or russet potatoes, peeled and each cut in half lengthwise 2 tbsp (30 mL) flour 1 1/2 cups (375 mL) grated Gruyère cheese 1 1/2 cups (375 mL) mushroom broth (see note)
1. Preheat the oven to 400 F (205 C). Lightly grease a 9-by13-inch (22.5-by-33-cm) baking dish with a little oil (or coat it with cooking oil spray).
2. Heat oil in a large pot over medium-high heat. Once it shimmers, stir in onion and red bell pepper; cook, stirring frequently, until the onion starts to become translucent, 5 to 6 minutes.
3. Stir in trimmed mushrooms, thyme, salt and black pepper; cook until the mushrooms have browned and cooked down a bit, 2 to 3 minutes. Turn off heat.
4. Cut the potato halves crosswise as thinly as you can (into half moons, no thicker than 1/4 inch/6 mm). The yield should be about 6 cups (1.5 L).
5. Layer half the sliced potatoes in the baking dish and then sprinkle evenly with 1 tablespoon (15 mL) of the flour.
6. Spread mushroom-bell pepper mixture over the potatoes, then scatter one-third of the grated Gruyère over that layer.
7. Use the remaining potato slices to build the next layer, then sprinkle with the remaining tablespoon (15 mL) of flour. Pour the mushroom broth over everything and top with the rest of the cheese.
8. Cover tightly with aluminum foil; bake (middle rack) for 30 minutes, then uncover and bake until potatoes are tender and the top is crusty and golden brown, another 30 minutes. Let stand at least 10 minutes before serving.
Note: If you can’t find commercially prepared mushroom broth, pour 2 1/2 cups (625 mL) boiling water over 1/2 cup (125 mL) dried sliced mushrooms, such as shiitake, and let them soak for at least 20 minutes. Strain through a fine-mesh sieve into a large liquid measuring cup. You’ll have extra which can be refrigerated for up to 2 weeks or frozen for up to 3 months. The soaked, dried mushrooms can be rinsed, sliced and added to the mushrooms in this dish.