Souffleed Sweet Potatoes

Preparation

1. Preheat the oven to 375 degrees.

2. Bake the sweet potatoes in their skins until they are tender. Remove from the oven and cut them in half lengthwise and scrape the flesh into a large bowl.  Mash along with the butter, lime juice, and salt.  Set aside to cool.

3. In a bowl using an electric mixer, beat the egg whites and cream of tartar until they are soft meringue peaks.  Set aside.  In a separate bowl, beat the egg yolks lightly with a fork.

4. Gradually beat the egg yolks into the cooled sweet potato mash. If the mixture seems stiff, add a little milk, 1 tablespoon at a time. You need just enough to make a thick puree that easily drops off a spoon. Stir in the cilantro, if using.

5. With a spatula, add 1 tablespoon of the egg white mixture to the sweet potatoes to break them up, then in batches, gently fold in the rest of the egg whites until they are combined with the sweet potatoes. The mixture should be soft and airy and not overly blended with streaks of egg whites remaining in the mixture.

6. Gently pile the mixture into a greased gratin dish and bake on a middle shelf in the oven until puffy and golden, about 30 to 35 minutes. Do not open the door while it is cooking or it will collapse! Serve immediately!