Here is a video explanation of making Compost Tea from Comfrey plants. You can put the leaves in a bucket to ferment for up to 2 weeks, then dilute the mixture 1 part fert to 4 parts water (you can guess). I just dip my watering can in and scoop some up then add water to the top of the can. It does get quite funky, and you want to use it quickly so mosquitoes don't hatch in the standing water. If they are unwieldy and you have more than you need for the fertilizer, you can cut the leaves and use them as mulch (just put the leaves on the ground to dry). Be careful not to let them root at the joining stems or you will have extra plants soon enough.
I know the quality of the video is not the best and I need to speak louder; I was using a tripod and since I cut the plant down to talk about it, I couldn't do a re-take!
I hope to make more videos about growing and making products from herbs soon, so subscribe to my channel on youtube if you would like to learn more. Enjoy!