01 - Pour 1/2 cup of the fruit juice into a medium saucepan. Sprinkle the gelatin powder evenly over the surface and let it sit undisturbed for 5 minutes until the mixture appears slightly thickened and the gelatin has absorbed the liquid.
02 - Place the saucepan over low heat and stir constantly until the gelatin dissolves completely and the liquid is smooth. Do not allow the mixture to come to a boil, as high heat can weaken the gelatin's setting power.
03 - Remove the saucepan from the heat. Pour in the remaining fruit juice along with the collagen peptides, honey or maple syrup if using, and the lemon juice. Whisk vigorously until the collagen is fully dissolved and the mixture is completely smooth with no visible lumps.
04 - If incorporating diced fresh fruit, gently fold the pieces into the mixture at this stage, distributing them evenly throughout the liquid.
05 - Carefully pour the liquid into silicone candy molds or a parchment-lined 8x8-inch baking dish, dividing it evenly. Tap the molds or dish lightly on the counter to release any trapped air bubbles.
06 - Transfer the molds or dish to the refrigerator and chill for at least 2 hours, or until the jellies are fully firm and hold their shape when gently pressed.
07 - If using a baking dish, lift the set jelly block out and cut it into uniform small cubes. Pop individual jellies out of silicone molds. Serve chilled or store for later enjoyment.