Crush the raspberries in a food processor 1/3 at a time and blend until puréed. Rinse a pot with water and then pour the berries into the pot.
Add the sugar and lemon juice and turn the heat to medium.
Once it begins to simmer and bubbles begin to form, leave it alone and let it simmer for 15 minutes. Use a spatula to stir up the bottom.
It will become glazed and the bubbles will disappear. Let it boil down for 10 more minutes without letting it burn. Once it becomes the same texture as jam, turn off the heat.
Line 2 baking trays with paraffin paper, wax paper, Silpat, or another type of non-stick parchment paper.
Pour the boiled mixture from Step 4 into the trays from Step 5 and use a spatula to spread it out until 3 mm thick.
Place into an oven preheated to 75°C (170°F) and bake for 3-4 hours to dry it out. When done, it should be just a tad sticky when touched.
Place on a cooling rack and let it cool. Cut into your choice of size.
If you place it on wax paper and roll it up, it will be just like store bought "Fruit by the Foot" or "Fruit Roll-ups!"
Store in a Tupperware (or plastic) container and it will keep for about 1 week at room temperature. If you make it on the weekend, you can put them in the kids' lunchboxes during the week.
Story Behind this Recipe
"Fruit by the Foot" and "Fruit Roll-ups" are popular children's snacks in America.
Since I try my best to avoid giving my children food coloring and additives, I make these by hand. It's easy to do and additive-free. You can even decrease the amount of sugar and most of all, it's safe to eat.
You can make this with puréed watermelon, blueberries, mango, blackberries, peaches, or kiwi by following the same exact Steps. Depending on the amount of juice in the fruit, the baking (dehydrating) time will change. If you use a sugary fruit such as mango, watermelon, or white peaches, you don't even need to add sugar and it will still be delicious.