Preheat oven to 350 degrees F (175 degrees C).

Place egg yolks into a large bowl; place egg whites in a separate glass or metal bowl.

Fit pie crust into a 9-inch pie dish. Spread rhubarb into bottom of crust. Whisk 1 cup sugar, half-and-half, flour, and salt into egg yolks until smooth. Pour mixture over rhubarb.

Bake in the preheated oven until pie crust is browned and filling is set, 50 to 60 minutes.

Beat egg whites until stiff using an electric mixer; gradually beat 1/4 cup sugar and cream of tartar into egg whites to make a glossy meringue. Spoon meringue over pie filling, going right to the edge of the crust and covering all the filling. Use a spoon or spatula to make decorative swirls in the meringue.

Return pie to oven and bake until meringue is lightly browned, 10 more minutes. Best served slightly warm.