In a medium saucepan, combine the raspberries and granulated sugar over medium heat.

Cook the mixture, stirring gently, until the raspberries break down and the sugar dissolves, about 5-7 minutes.

Remove the saucepan from heat and stir in the lemon juice and vanilla extract, if using.

Allow the mixture to cool slightly, then pour it through a fine mesh sieve into a bowl to strain out the seeds. Use a spatula to press down on the solids to extract as much liquid as possible.

Discard the seeds and let the coulis cool completely before serving or storing.

The raspberry coulis can be drizzled over desserts, pancakes, or used as a topping for yogurt.