Ensure equal amounts and similar sizes of rhubarb and strawberries for even cooking and balanced flavor., Adding flour (or cornstarch) to the fruit mixture helps thicken juices and prevent runniness., Press topping lightly to adhere and maintain crunch., Cool completely before covering leftovers to preserve crispness; reheat in oven to restore topping crunch., If using frozen fruit, thaw and drain excess liquid before use and consider adding extra flour or cornstarch., Always discard rhubarb leaves as they are inedible and potentially harmful., The recipe can be halved and baked in smaller dishes or ramekins; adjust baking time accordingly., To make gluten-free, substitute all-purpose flour with gluten-free blends and use certified gluten-free oats., For vegan versions, replace butter with coconut oil or vegan butter alternatives and consider sugar substitutes like maple syrup or coconut sugar., Flavor variations include adding nuts (pecans, walnuts, pistachios), swapping strawberries for other berries, and adding lemon zest or vanilla/almond extract.