Organic tea made of earthworm castings and a handful of soil

Forget the tea and just top dress the castings and water normally.

 

What would be the purpose of said tea?

 

Plants look really good, your soil is doing great, I wouldn't use a compost tea on it.

 

Castings tea wont give you much in the ways of available nutrients, its usually made for the purpose of propagating microbes/fungi and in container gardening is very much redundant and gives no true benefit over just taking your castings and dressing the top of the soil.

If you want to make teas to provide nutrients to your plants look into making kelp, alfalfa or neem tea (or a mix). sprouted seed tea or top dressing with malted barely is also good for providing enzymes to help break down organic matter in the soil and make nutrients available.

You can check my notes compilation for recipes to make these tea.
All Organic Recipes and Notes Compilation

As a side note: If you pick up the habit of top dressing with organic amendments (kelp, alfalfa, neem, malted barley) on a regular basis you wont need to make teas as you will already be providing the soil with what it needs. A tea will be more readily available however if need something more immediate.

 

If you havnt already I suggest you skim the no till threads. at least first 50 pages of both the new and old threads. Some great info on organic growing.
No-Till Gardening
No-Till Gardening: Revisited