Source: Joy the Baker, who adapted it from Simply Recipes
1 cup sugar, for a less sweet lemonade, take the sugar down to 3/4 cup
1 cup water to make the simple syrup
1 cup fresh lemon juice
4 cups cold water
2 Tablespoons to 1/4 cup raspberry sauce, depending on how much raspberry you like
Make simple syrup by heating the sugar and water in a small saucepan until the sugar is dissolved completely.
While the sugar is dissolving, use a juicer to extract the juice from 4 to 6 lemons, enough for one cup of juice. (I don't have a juicer so I just squeezed the lemons and ended up using 7 lemons to get enough juice - I heated them up in the microwave and then rolled them on the counter before cutting and squeezing to release more of the juice)
Add the juice and the sugar water to a pitcher. Add 4 cups of cold water, more or less to the desired strength. Add the prepared raspberry sauce and stir to combine. Refrigerate 30 to 40 minutes. If the lemonade is a little sweet for your taste, add a little more straight lemon juice to it.
Serve over ice.
Easy Raspberry Sauce
1/2 of a 12-ounce bag frozen raspberries, thawed (I used a pint of fresh raspberries)
1 tablespoons sugar
1 tablespoons water
Place the thawed raspberries in the bowl of a food processor fitted with a blade attachment. Add sugar and water and mix until the raspberries form a smooth puree. Transfer raspberry puree to a fine mesh strainer fit over a bowl. Press the puree through the strainer, until only the raspberry seeds and a bit of pulp remain the the strainer, and a beautiful raspberry sauce is all that’s in the bowl.