The secret to this flavorful sauce is not to overcook the sorrel leaves but to lightly steam them, ensuring they don’t lose their fresh slightly bitter–sharp lemony flavor.
Butter the cazuelitas and place on a baking sheet in a cold oven; set the temperature at 350°F.
In a small nonreactive saucepan, cook the sorrel with 2tablespoons of the cream until it melts, about 3 minutes. Season with the salt, pepper, and nutmeg.