Preheat the oven to broil.
In a stand mixer bowl, place the egg whites, sweetener and salt. If you don't have a stand mixer, use a large bowl.
Bring a saucepan with a few inches of water to a simmer. Set the mixing bowl over the simmering water making sure the water doesn't touch the bottom of the bowl.
Continuously stir the mixture until the whites are warm to the touch, about 4-5 minutes. If you're using a powdered sweetener, check by dipping your finger into the mixture and rubbing it between your fingers making sure the sweetener is completely dissolved.
Remove the mixing bowl and bring to stand mixer base. Lock in place with the whisk attachment or use an electric hand mixer. Beat on medium speed for about 2 minutes until it's foamy.
Gradually increase speed until the meringue has stiff peaks, about 4-5 minutes.
Spread meringue on top of the lemon curd filling to the edges of the crust of the pie. Smooth over the top, making swirls with the back of a spoon or spatula.
Place meringue under the broiler for about 1-2 minutes until golden brown. Careful not to burn. Option to use a blow torch if you like.