Meringue with Strawberry Rhubarb Sauce

For the meringues:
Line a large baking sheet with parchment paper and draw eight 3-inch circles evenly spaced on paper. Turn paper over.

Preheat oven to 200°F with rack in middle of oven. Beat egg whites, lemon juice and salt with an electric mixer on medium speed until soft peaks form. Beat in sugar, 1 tablespoon at a time until meringue is stiff and glossy, 2 to 3 minutes.

Divide meringue mixture among circles and spread with the back of a spoon, making a slight indentation in the center of each meringue to make a nest. Bake until meringues are dry to the touch, 2 to 3 hours. Turn off oven and let meringues cool completely, about 30 minutes to 1 hour. Meringues will crisp as they cool.

Loosen meringues with a spatula and keep at room temperature in an airtight container, layers separated with parchment paper.

For the strawberry/rhubarb sauce:
Purée strawberries with sugar and lemon juice in a food processor, then force purée through a fine mesh sieve into a bowl. Chill until ready to use.

Roast rhubarb: Preheat oven to 375°F with rack in middle. Arrange rhubarb in 1 layer in a lightly oiled shallow baking pan (preferably nonstick) and toss with sugar and corn starch. Roast in middle of oven until tender, 15 to 25 minutes, then cool in pan on a rack.

To serve, put meringues on plates and divide rhubarb among nests. Drizzle with strawberry sauce.