For a smoother sauce, ensure the cornstarch is fully dissolved in the water before adding it to the raspberry mixture. Adjust the amount of red currant jelly to your preference. If you prefer a tarter sauce, use slightly less. For a sweeter sauce, use a bit more. This sauce can be made ahead of time and stored in the refrigerator for up to 3 days. If you don't have a sieve, you can skip this step, but the sauce will have a slightly seedy texture. Try adding a splash of orange liqueur or a pinch of cinnamon for an extra layer of flavor.