This is a modified version of a recipe I got from Betty Crocker's New Cookbook. It has a wonderful lemon flavor and isn't too difficult to make.
Please note that this recipe is only soy-free if you use all soy-free ingredients, and is fish, wheat, egg and nut-free.
3/4 Cup white sugar
3 Tablespoons cornstarch
1/8 teaspoon salt
2/3 Cup water
1 Tablespoon salted, full-fat butter
1/4 Cup lemon juice
1. Mix sugar, cornstarch and salt in 1 1/2-quart saucepan.
2. Gradually stir in water and make sure that it is well incorporated.
3. Cook over medium heat, stirring constantly, until mixture thickens and boils; boil and stir one minute then remove from heat.
4. Stir in butter until it is melted fully.
5. Gradually stir in lemon juice and press plastic wrap onto filling.
6. Refrigerate about 2 hours or until set.
Please note that any cakes or pastries that you fill with this filling need to be refrigerated.