This small batch strawberry pie filling is made from scratch with fresh strawberries, no jello and no canned shortcuts. It's soft, spoonable, and jam-like.
Hull 16 ounces of strawberries and cut them in half, quartering any large ones so the pieces are about the same size. Set aside roughly a third of them (about 6 ounces) to fold in fresh at the end.
Add the rest of the strawberries and the sugar to a 2-quart saucepan. Bring to a boil over medium heat, stirring often, then cook for 1 minute as the berries soften and release their juice.
In a small bowl, whisk the cornstarch and water until smooth with no lumps. Slowly stir the slurry into the boiling strawberries, then bring everything back to a boil.
Lower the heat to a simmer and cook, stirring often, for 5 to 7 minutes. The filling is ready when it thickens and turns from cloudy to a clear, deep red. Cornstarch needs this time and heat to set, so don't rush it.
Take the pan off the heat and pour the filling into a medium bowl. Let it cool for about 30 minutes. This step matters, because folding berries into a hot filling cooks them and thins it out.
Once the filling has cooled, gently stir in the reserved berries so they stay whole.
Cover and refrigerate for at least 3 hours. The filling keeps thickening as it chills and is ready once it's set.
Notes
Use ripe strawberries. The filling is mostly fruit, so the berries carry the flavor. Ripe, in-season strawberries give you the sweetest, most concentrated result. Smaller berries tend to be sweeter than large ones.Whisk the cornstarch with water first. Stirring the cornstarch into a smooth slurry before it goes in the pot keeps it from clumping when it hits the hot berries. Adding dry cornstarch straight to the pan leaves lumps you can't whisk out.Cook the cornstarch long enough. Cornstarch needs heat to thicken and to lose its raw, starchy taste. Let the filling simmer the full 5 to 7 minutes until it turns from cloudy to clear red. If you rush this, the filling stays thin and can taste a little chalky.Cool the cooked filling before folding in the fresh berries. Stirring fresh strawberries into a hot mixture starts to cook them and pulls out their juice, which thins the filling. Letting it cool first keeps those berries whole and the texture right.Let it chill fully. Cornstarch fillings keep thickening as they cool, so the filling firms up in the refrigerator over the full 3 hours. Don't judge the final texture straight off the stove.Note: This is a jam-like filling, not a gelatin-based one. It won’t have the same texture or firmness as a filling made with Jell-O.