These mini pavlovas--the meringues at least--are adapted from How To Be a Domestic Goddess, a Nigella Lawson classic.
Preheat the oven to 350 F.
Line two baking sheets with parchment paper.
Using an electric mixer (handheld or stand mixer), whisk the egg whites with the salt until they hold firm (but not stiff) peaks. Gently add the sugar, a spoonful at a time, until the meringue is gleaming and satiny and holds stiff peaks. Sprinkle in the cornstarch, vanilla, and white wine vinegar, and fold in to combine.
Using a pastry bag with a large round tip or a plastic sandwich bag with the corner cut off, pipe nine 4-inch mounds of meringue onto the baking sheets. (Five on one sheet, four on the other.) Use the back of a spoon to create an indentation in the center of each mound.
Place the baking sheets in the oven, reduce the temperature to 300 F, and bake for 30 minutes. Turn off the oven and leave the meringues in the turned-off oven for 30 minutes more.
Remove the meringues from the oven to cool on wire racks. (You can transfer the entire parchment sheet to the wire rack.)
Once the meringues are completely cool, they can be stored in an airtight container for at least a day or two.
Cut the rhubarb lengthwise in half (if the stalks are already thin), or quarters (if the stalks are fat). The slice the pieces crosswise to create 2-inch batons.
Place the water, sugar, and kaffir lime leaves in a saucepan and bring to a boil. Reduce heat to a simmer, and simmer for 10 minutes.
Add the rhubarb to the simmering sugar syrup, return to a boil, then immediately remove the pan from the heat.
Leave the rhubarb to steep in the sugar syrup as it cools.
Once cool, use a slotted spoon to remove the rhubarb from the sugar syrup. If making ahead, place the rhubarb in an airtight container and refrigerate for up to 2-3 days.
Open the refrigerated cans of coconut cream and scoop out the cream that has settled at the top of the can, reserving the liquid underneath.
Place the scooped out cream in a large mixing bowl. Using an electric mixer, whip the coconut cream until it is smooth, light, and fluffy, adding a bit of the reserved liquid from the can if needed. Whisk in the superfine sugar.
Just before you're ready to serve the pavlovas, spoon a couple of tablespoons of coconut cream into the indentation in each of the meringues. Top each cream-filled meringue with seven or eight pieces of rhubarb.
If you don't eat corn products during Passover, just substitute potato starch for the cornstarch in the meringues--it works just as well.
You can either reserve the sugar syrup for another use, or bring it back to a boil for a few minutes to reduce it, and then drizzle it over the assembled pavlovas.
If you can't find rhubarb and/or kaffir lime, try topping these pavlovas with chopped mango tossed in a bit of lime juice!
Brands of coconut cream vary widely. This post offers some guidance on which brands whip up best.
For extra crunch, try topping the assembled pavlovas with toasted coconut flakes.