Potato and Sorrel Gratin

from Chez Panisse Vegetables, by Alice Waters

submitted by Anne Halsted

preparation time: 20 minutes plus cooking time

serves 8 to 10

about 24 large sorrel leaves

8 tablespoons unsalted butter, divided

3 pounds russet or Yukon Gold potatoes

salt and pepper

nutmeg

2 cups cream or milk

¼ cup grated Gruyère cheese

2 tablespoons grated Parmigiano-Reggiano cheese

Preheat the oven to 375 degrees.  Butter a large gratin dish.

Wash, stem, and coarsely chop the sorrel leaves.  Melt 4 tablespoons of the butter in a sauté pan, add the sorrel, and cook until the leaves are completely wilted and have turned olive green.  Transfer to a plate.

Peel and thinly slice the potatoes.  Layer half the potatoes in the gratin dish, season well with salt and pepper, and grate a little nutmeg over them. Spread the cooked sorrel evenly over the potatoes.  Make another layer with the rest of the potatoes and add enough cream or milk to almost cover them.  Season again with salt, pepper, and nutmeg.  Dot the surface with the remaining 4 tablespoons of butter and sprinkle with the grated cheeses.

Bake about 1 hour, until the surface is nicely browned and the liquid is almost completely absorbed.