[gil]

Here's an article about jelly-making in general

VM, you have the same problem as me re loadsa frozen blackcurrants !
Ditto juniper - they do take years to produce berries - I planted a bush about 3 years ago and it is still tiny and no berries.
However, the leaves smell of juniper, so can be used instead. But given how small the bush is, I am still wary of taking too many sprigs.

Blackcurrant and Juniper Jelly [using frozen currants]

3lb blackcurrants
a couple of cooking apples [fresh]
4 tsps juniper berries
sugar

1. Put currants into pan and measure out water to cover [prolly 2.5-3pints]; stew on low heat till tender, mashing down
2. Chop up and add apples, and stew on
3. Scald a jelly bag / old pillowcase with boiling water
4. Pour the fruit mix into it and set to drip through
5. Leave it overnight / for several hours, and wash out your pan
Later :
6. Measure the juice back into the pan [may be approx 3 pints]
7. On low heat, warm juice and add 14oz sugar per pint of juice; stir till dissolved
8. When all sugar crystals gone, crush the juniper berries in a mortar, and put in small jellybag/muslin, hanging into pan tied on to handle. Turn up heat, and boil to setting point reached. Squeeze/mash the bag of juniper and Take it out.
9. Pot into small jars that you have warmed in the oven.

Yield = approx 6-8 8oz jars

Or you can do a version that is half currants and half apples in weight. Still tastes very curranty.