For the lemon ice cream: Bring the milk to a simmer in a medium saucepan.
Whisk the egg yolks and sugar in a medium bowl until thick and light lemon colored, about 1 minute. Pour the milk into the egg mixture in a slow steady stream, whisking constantly to temper the egg yolks. Pour the mixture back into the saucepan and cook over low heat, stirring constantly, until the mixture thickens, 5 to 7 minutes. Remove from the heat and following this order stir in the lemon curd, lemon zest, cream and lemon juice, mixing well between each addition.
For the best results refrigerate overnight before churning in an ice cream machine according to the manufacturer's instructions.
Mix together the sugar and cream of tartar in a large mixing bowl.
Beat in the sugar mixture 1 tablespoon at a time, followed by the cornstarch mixture, also 1 tablespoon at a time, and mix until stiff peaks form.
Spread the meringue on top of the ice cream and torch.