Step 1

In a saucepan, whisk together the egg, sugar, and salt until the sugar dissolves.

Step 2

Add the starch, and about ¼ cup of the milk alternative. Whisk until the starch is dissolved. Whisk in the rest of the milk alternative.

Step 3

Place the pan over medium heat, and cook, while whisking, until the mixture begins to steam. Try not to let it boil. Turn the heat down to medium low (or low if needed) and continue whisking or stirring until the mixture thickens enough to coat the back of a spoon, about 5 to 10 minutes.

Step 4

Remove the pan from the heat, and whisk in the vanilla extract.

Step 5

Let the custard cool for a few minutes and serve, or pour it into a container and cool completely before covering and refrigerating. If you do not let the custard cool to room temperature before covering, it will break the custard down.