Special equipment: a candy thermometer
1. For the cupcakes: Preheat the oven to 350 degrees F. Line two 12-cup muffin tins with 18 paper liners (leaving 6 spaces empty) and spray the liners with the baking spray.
2. Sift together the flour, baking powder and salt into a medium bowl.
3. Put the butter and sugar in the bowl of a stand mixer fitted with a paddle attachment, or in a large bowl if using a hand mixer. Beat on medium-high speed until fluffy and pale yellow, 5 to 6 minutes. Add one egg at a time and continue to beat on medium speed, making sure each egg is fully incorporated before adding the next. Add the vanilla and orange zest and beat until combined. Reduce the speed to low and add a third of the flour mixture, followed by half of the orange juice; mix together to incorporate. Add another third of the flour and the rest of the orange juice, mixing to combine. Add the rest of the flour and mix just until combined; be careful not to over-mix the batter.
4. Divide the batter evenly among the 18 paper liners, about 1/4 cup in each. Bake, rotating the pans midway, until lightly browned around the edges and a toothpick inserted in the middle of the cupcakes comes out clean, 18 to 20 minutes. When cool enough to handle, remove the cupcakes to a wire baking rack to cool completely.
5. For the meringue frosting: Heat 1/2 cup water, the sugar and salt in a small saucepan until a candy thermometer inserted in the mixture registers 240 degrees F. In the meantime, put the egg whites and lime juice in a medium bowl and start beating with the whisk attachment until they reach soft peaks. Carefully pour the hot sugar syrup in a thin steady stream into the egg whites as they're being whisked. Keep whisking until the egg whites are stiff and glossy, about 5 minutes; the bottom of the bowl should have completely cooled at this point. Add the lime zest and whisk just to combine.
6. To assemble the cupcakes: Scoop out about a teaspoon of cake from the middle of each cupcake using a melon baller or a teaspoon measuring spoon. Spoon about a teaspoon of jelly in the middle of each and cut up some of the cake scraps to cover the holes. Pipe or dollop the meringue frosting on top.