Heat oven to 250° with racks set in upper and lower thirds. Using a 3½-inch cutter or bowl, trace 6–7 rounds on each of two sheets of parchment paper. Transfer parchment paper to baking sheets, traced-side down.

Combine sugar and egg whites in the (metal) bowl of a stand mixer. Set bowl over a saucepan filled with 1 inch of simmering water, making sure water doesn’t touch bottom of bowl. Heat sugar mixture, whisking constantly, until sugar has dissolved and mixture registers 160–165°, about 6 minutes.

Secure bowl to stand mixer fitted with whisk attachment and whip mixture on high speed until stiff peaks form and meringue bright white, smooth and glossy, about 4 minutes; scrape down side of both.

Whisk together vinegar, cornstarch, vanilla, and cardamom in a small bowl. Add vinegar mixture to whipped meringue and whip on high speed until combined, about 10 seconds.

Using two spoons, scoop meringue into the center of each round. Using a spoon, spread meringue to fill circles then create an indentation in the middle of each circle.  

Bake meringues until exteriors are dry and crisp, pale and slightly creamy in color, and cleanly release when gently lifted with a thin spatula, 50–55 minutes.

Turn off oven, prop open door with a wooden spoon, and let meringues cool in oven for 1 hour. Transfer to a wire rack to cool completely.

To serve, gently toss together citrus and allspice. Spoon a heaping tablespoon or two of cranberry curd into center of each meringue then layer about ⅓ cup citrus mixture on top of curd, top with pomegranate arils and sprinkle with just a touch of salt; serve.