Preheat oven to 375°F. Put the raspberries in a saucepan with the orange zest and juice. On low flame, cook just until the raspberries are hot and have broken down, but do not boil. Using a sieve, strain the juice from the seeds, pressing to get as much raspberry juice as you can. You should have about ¾ cup of thick raspberry juice. Set aside in a bowl.

Cut the rhubarb stalks in half lengthwise, then cut on a sharp diagonal into 1-inch pieces.

Stir the rhubarb and maple syrup into the raspberry sauce. Transfer to a 9 x 13-inch casserole and bake until the rhubarb is just tender but still holding its shape, about 15 minutes. Resist the urge to bake longer--the fruit softens as it cools.

Using a slotted spoon, carefully remove the rhubarb. Stir in the vanilla, balsamic vinegar, and several grinds of black pepper.

Stir the strawberries into the raspberry sauce. Place meringues on plates. Spoon rhubarb to one side and strawberries into the center. Drizzle sauce around the plate. Sprinkle with pistachios and freshly ground black pepper.

Preheat oven to 200°F. Line 2 large baking sheets with parchment. Pour the bean liquid (aquafaba) through a strainer. With an electric mixer or stand mixer with whisk, whip the liquid with the cream of tartar until white and foamy, 2 to 5 minutes, less with a stand mixer. The liquid will double in volume.

Continue whipping, adding the sugar 1 tablespoon at a time. Whip until the meringue forms stiff glossy peaks. This can take a while, 5 minutes or more, again depending on your mixer. Make a slurry with the arrowroot, vinegar, and vanilla. Add the slurry and whip some more.

Scoop 1/3 cup mounds onto the parchment-covered baking sheet. (I use a #16 cookies scoop) Use the back of a spoon to hollow out the centers. Make the hollows deep, because they are not as deep when the meringues expand in the oven.

Bake about 2 hours, until the meringue is dry. (see note)