Place the non-dairy milk, sugar and salt in a saucepan and cook over a medium-low heat, while whisking frequently. Do this until the volume is reduced to 1 cup which should take about a couple hours. Don't let the mixture boil aggressively; a very mild simmer is ok. Keep in mind that you'll have to reduce heat as the mixture gets reduced so you don't burn it. Have a measuring cup handy so you can measure the mixture as you go along. When 1 cup of mixture remains, whisk in the vanilla extract.

Transfer the condensed non-dairy milk to a container, cover and place it in the refrigerator for several hours until it cools to at least room temperature. This will ensure that your condensed milk is the proper thickness for most uses. Alternatively, you can use a slow cooker to condense the non-dairy milk. Just set it to high, leave the top off and cook for about 7 hours. Don't worry if you reduce the mixture a little too far. Just place it in a food processor with enough water to bring it back up to 1 cup and process it to combine. Store in a covered container in the refrigerator for up to 2 weeks. This recipe makes about 1 cup (237 mL) of Vegan Condensed Soy, Rice, Nut or Coconut Non-Dairy Milk.