Hull the strawberries and dice them into ½-inch pieces.

In a medium saucepan, combine the strawberries, sugar, 2 tablespoons water, and lemon juice. Place over medium-high heat and bring the mixture to a simmer while stirring frequently. Cook until the strawberries are nearly submerged in their juices, about 3 minutes.

Reduce the heat to medium-low and cook, stirring occasionally, for 10 to 15 more minutes, until the sauce is reduced by about one-third, the strawberries have mostly broken down, and the consistency is syrupy. Remove from the heat and stir in the vanilla. Transfer to a bowl or jar and let cool to room temperature. (The sauce will continue to thicken as it cools, especially with refrigeration.)

Store covered in the refrigerator for up to 5 days.