I use this kind of method quite a lot especially with weeds that have gone to seed or have resilient roots (the idea is that, since I only practice cold composting, seedy weeds or persistent roots would survive in the compost heap). I let the vegetable matter rot completely in the water, and eventually the resulting slimy liquid becomes quite smelly. This is accomplished in 2-3 weeks. All the seeds and roots rot together with the rest of the plant and are no longer viable. After you use the liquid as feed, you can dump the remaining vegetable matter onto your compost heap.
Ganado Mage wrote:the most basic recipe is
1 to 3 ratio of vinegar to oil
mustard, salt & pepper to taste
branch with optional flavor like herbs, honey, sugar etc from the base.
you an substitute lemon or lime juice for the vinegar for variation.