Instructions

1. Place racks in upper and lower thirds of oven; preheat to 325°. Combine mushrooms, thyme sprigs, and garlic on a large rimmed baking sheet. Season generously with kosher salt and pepper; drizzle with oil. Toss to coat mushrooms, then spread out in an even layer. (Make sure not to crowd the mushrooms on the baking sheet; otherwise, they’ll steam instead of getting crispy.) Transfer to upper rack in oven and let mushrooms roast while you cook the grits for about 25-30 minutes.
2. Heat the 4 cups water in a heavy-bottomed saucepan until just simmering.
   While the milk is heating, put the stone-ground grits into a large mixing bowl and cover with cool water. Stir grits into the simmering water. Cook, stirring often, until the grits are tender to the bite and have thickened to the consistency of thick oatmeal. As the grits thicken, stir them more often to keep them from sticking and scorching. Regular grits are done in about 20 minutes, but stone-ground require an hour or a little more to cook, and you will have to add additional water as needed.
   Season the grits generously with salt and stir in the butter. Remove from heat and let rest, covered, until serving. Serve hot.
3. While the grits are simmering, crank up oven temperature as high as it will go (but don’t broil). Continue to cook mushrooms until crisp around the edges, 5–10 minutes longer. (They should be done 35-40 minutes.)
4. Remove mushrooms from oven; drizzle with vinegar. Toss to coat; let cool slightly.
   Divide grits among bowls and top with mushrooms, thyme leaves, sea salt, and black pepper.