In a 2-quart saucepan or frying pan combine strawberries and sugar.
Mix the cornstarch with 2 tablespoons water and vanilla
Pour that mixture over the berries and stir to combine
Heat over medium heat until it simmers, the berries soften and juices are released creating the sauce.
Add more water if you'd like a thinner sauce, or if the berries are not juice, more dry and you need more sauce, add up to a cup of water. If you add more water than that, add some more sugar and cornstarch.
Remove from heat, allow to cool 10 minutes.
Pour it into a glass canning jar or similar.
Serve or store in the fridge up to a month.
Reheat before serving for best flavor.