This frozen strawberry rhubarb pie filling lets you capture the bright, tart-sweet taste of early summer and use it months later. The filling is cooked just enough to soften the rhubarb and meld the flavors, then thickened with cornstarch so it holds together beautifully in a pie without turning watery. Because it’s frozen raw, not canned, the texture stays closer to fresh fruit, and you can make a pie in minutes whenever the craving hits.
Ingredients
- 6 cups fresh or frozen rhubarb, cut into 1-inch pieces (about 2 pounds)
- 4 cups fresh or frozen strawberries, hulled and halved (about 1.5 pounds)
- 1 1/2 cups granulated sugar
- 1/4 cup cornstarch
- 1 tablespoon lemon juice
- 1/2 teaspoon vanilla extract
- 1/4 teaspoon salt
Instructions
- If using fresh fruit, wash and prep the rhubarb and strawberries. If using frozen, measure them while still frozen; no need to thaw.
- In a large bowl, combine the rhubarb, strawberries, sugar, cornstarch, lemon juice, vanilla, and salt. Stir gently until the fruit is evenly coated and the sugar begins to dissolve.
- Let the mixture sit at room temperature for about 30 minutes. This draws out the fruit’s juices and helps the sugar and cornstarch dissolve fully, preventing lumps later.
- Transfer the mixture to a large pot or Dutch oven. Cook over medium heat, stirring frequently, until the mixture comes to a simmer. Reduce heat to low and cook for about 5 minutes, stirring constantly, until the rhubarb is just tender and the liquid has thickened to a syrupy consistency. The fruit should still hold its shape.
- Remove from heat and let cool completely to room temperature. This is important—if you freeze the filling while warm, it will form ice crystals and become watery.
- Once cool, spoon the filling into freezer-safe containers or heavy-duty zip-top bags. Leave about 1 inch of headspace in containers to allow for expansion. For bags, press out as much air as possible before sealing.
- Label each container with the date and freeze. The filling will keep for up to 6 months.
Tips
- Thickening adjustment: If your fruit is very juicy, add an extra tablespoon of cornstarch. If you prefer a looser filling, reduce the cornstarch to 3 tablespoons.
- Freezer bags vs. containers: Freezer bags lie flat and stack easily, but they can leak if not sealed well. Use a double bag for extra security. Rigid containers protect the filling better but take up more space.
- Don’t overcook: The filling should be slightly undercooked when you freeze it, because it will cook more when you bake the pie. Overcooking now makes the fruit mushy later.
- Measure accurately: Rhubarb’s tartness varies; if your rhubarb is very tart, add an extra 1/4 cup of sugar. Taste the filling before freezing—it should be slightly sweeter than you want the final pie to be, because freezing dulls sweetness.
Serving Suggestions
This filling is perfect for a classic double-crust pie. Simply thaw the filling in the refrigerator overnight, pour into a prepared pie crust, top with a second crust, and bake at 375°F for about 50 minutes, or until the crust is golden and the filling is bubbly. It also works beautifully in hand pies, galettes, or as a topping for vanilla ice cream or cheesecake. For a quick dessert, spoon the thawed filling over warm biscuits or pound cake.
Variations
- Spiced version: Add 1/2 teaspoon of ground cinnamon and a pinch of ground nutmeg to the filling before cooking.
- Orange twist: Replace the lemon juice with orange juice and add 1 teaspoon of orange zest.
- Less sugar: Use 1 cup of sugar instead of 1 1/2 cups, and add 1/4 cup of honey or maple syrup for a more complex sweetness.
- Berry blend: Swap 1 cup of strawberries for raspberries or blueberries for a different flavor profile.
Storage and Reheating
Store the frozen filling in the freezer for up to 6 months. Once thawed in the refrigerator, use it within 3 days. Do not refreeze thawed filling, as the texture will become mushy. To reheat, place the thawed filling in a saucepan over low heat, stirring occasionally, until warmed through. If you’re using it in a pie, there’s no need to preheat the filling—just spoon it into the crust and bake as directed.
Frequently Asked Questions
Can I use frozen fruit directly without cooking? Yes, but the filling will be more watery and the cornstarch may not dissolve evenly. Cooking briefly ensures the filling sets properly and freezes well.
Why did my filling turn out runny after baking? This usually happens if the filling wasn’t cooked long enough before freezing, or if the fruit released extra juice during baking. Make sure you cook the filling until it’s thick and syrupy, and let it cool completely before freezing.
Can I use this filling for a lattice-top pie? Absolutely. The filling is thick enough to hold up under a lattice crust. Just be sure to let the pie cool for at least 2 hours after baking so the filling sets.
How do I thaw the filling quickly? Place the sealed container in a bowl of cold water for about an hour, or microwave it in short bursts, stirring between each. For best results, thaw overnight in the refrigerator.
Is it safe to leave the filling out at room temperature? No. Because the filling contains fruit and sugar, it can ferment if left out for more than 2 hours. Always refrigerate or freeze promptly after cooling.
Can I double the recipe? Yes, but cook it in batches or use a very large pot to avoid overflowing. The cooking time may be slightly longer, but the process is the same.