While working in the kitchen, I've learned to be resourceful with past-prime foods. We frequently get transfers from both the produce and meat departments, and craft them into fine foods.
One of the things we make is berry compote, which goes into parfaits and various pastries. It's quite simple to make, and puts those mushy berries to good use.
Today I found a whole bunch of strawberries and grapes on clearance at the local produce grocer - only $1 each. So I made some grape-strawberry jam.
Start off by cutting the fruit into small bits so that it will cook down evenly, and spread nicely on toast. Toss it into a pot with a bunch of sugar and a dash of salt. Bring it to a rolling boil; keep it there for 30 to 45 minutes, until it has reduced to about 1/4 of its original volume and has reached the desired jammy texture. Test the texture with a wooden spoon. Finally, toss it into the freezer for 10 minutes to cool, pour it into a rinsed jar, and refrigerate.
Because grapes have lots of pectin, I didn't add any while making this jam. Commercial pectin is derived from apple skins and citrus skins - the latter of which have a very high concentration.
NOTE: I over-estimated the amount of pectin in the grapes; it was not enough to compensate for the utter lack of pectin in strawberries, so I ended up with a compote instead of a jam Still tastes great though.