
Step 1 · Brown the Mushrooms
Heat the olive oil in a Dutch oven over medium-high. Add the mushrooms and cook, stirring occasionally, until deeply browned, about 8 minutes. Transfer to a bowl.
Step 2 · Saute the Vegetables
Add the onion and carrots to the pot and cook until softened, about 5 minutes. Stir in the garlic and cook 1 minute more.
Step 3 · Build the Base
Stir in the tomato paste and cook 1 minute. Sprinkle the flour over the vegetables and stir constantly for 1 minute.
Step 4 · Add Stock and Potatoes
Pour in the vegetable stock a little at a time, stirring and scraping up any browned bits. Add the potatoes, thyme, salt, and pepper.
Step 5 · Simmer
Bring to a simmer, partially cover, and cook until the potatoes are tender, about 20 minutes. Return the mushrooms and simmer 5 minutes more to thicken.
Step 6 · Finish and Serve
Discard the thyme stems. Taste, adjust the seasoning, and serve hot.