Ingredients for 6 -8 servings:
1 pound rhubarb after trimming both ends (4+ cups, diced)
1 cup water
1 cup sugar
3/4 cup egg whites at room temperature
3 tablespoons confectioners' sugar
3 tablespoons cornstarch
Preheat the oven to 325 degrees. Butter the interior of a 7-8 cup souffle mold and coat it with granulated sugar. Reserve an oven-proof dish large enough to hold the souffle mold and deep enough fill with 2" water. Heat one quart water to a boil and reserve.
Halve the rhubarb stems lengthwise and then across into one-half inch pieces. Place the water and sugar in a heavy skillet, and bring water to a simmer, shaking rather than stirring to dissolve the sugar. Add the rhubarb to the simmering syrup, cover and cook for 5 minutes. Uncover, and continue cooking another 10 minutes until the rhubarb mixture is very thick and reduces to 2 1/4 cups. Pour it into a large mixing bowl and allow it to cool.
Wipe the bowl and whisk with distilled vinegar before beating the egg whites. Alternate beating in tablespoons of sugar and cornstarch when the whites reach soft peaks. Fold the whites into the rhubarb jam gently in three installments leaving streaks to avoid over-folding. Transfer the souffle mixture carefully into the prepared mold, and set this mold into a larger pan. Pour hot water to come two inches up the side and bake for 40 minutes.
Serve the souffle by lifting off a portion of the browned top and then scooping out the interior underneath.
HOLDING AND REHEATING A SOUFFLE
The souffle can be refrigerated as long as 30 minutes before baking.
The souffle can be prebaked and allowed to cool to room temperature. It will puff up again once the water bath is reheated, and the souffle placed in a 325 degree oven for 15 -20 minutes.