Whisk together sugar and cornstarch in a small bowl.
In a medium saucepan, combine frozen strawberries and the sugar-cornstarch mixture.
Cook over medium heat until thick and bubbling, about 5 – 10 minutes.
Use a potato masher or fork to smush the strawberries and speed up the process.
Remove from heat and stir in vanilla and lemon juice.
Strain through a fine mesh strainer to remove seeds and pulp. Let cool completely.
Use sauce right away or store in an airtight container. You can also quarter fresh strawberries and toss with the cooled strawberry sauce for serving as well.
Notes
This makes about 1½ cups of strawberry sauce.
One serving is approximately 2 tablespoons.
Smash the strawberries ahead of time with a potato masher or fork to speed up the process.
Take time to taste the strawberry sauce and adjust with more lemon juice or more vanilla as desired.
After cooling to room temperature, store leftovers in an airtight container in the refrigerator.