Prepare the fruit as needed: Remove stems, pits, seeds, and skin, as needed.
Chop large fruits into small pieces. Berries can be left whole.
Cook the fruit until it starts to break down: Transfer the fruit to a saucepan and set over medium heat. Cook until the fruit breaks down and becomes syrupy, 5 to 10 minutes.
Mash the fruit with the back of a spatula or a potato masher, leaving it as smooth or as lumpy as you like.
Stir in the honey and lemon juice: Off the heat, stir in 1 tablespoon of the honey and lemon juice. Taste and add more honey or lemon juice to taste.
Stir in the chia seeds and let stand 5 minutes, until thickened: This won’t quite reach the firm consistency of regular jam, but it will noticeably thicken. If you’d like a thicker consistency, especially with very juicy fruits, stir in more chia seeds 1 teaspoon at a time.
Transfer to a jar or other storage container: Once the jam has cooled to room temperature, transfer it to a jar or other storage container. Store in the fridge for about 2 weeks. The jam will thicken further and become more set once completely chilled. The jam can also be frozen for up to 3 months; thaw in the fridge before using.