'Organically' - I'd choose things such as blood and bone meal, ancient and crumbly steer manure (aka cowpats), pelletised sheep manure/wool. For the tomatoes I'd also add in wood ash for the potash content. Use untreated wood - even brushwood/pruning wood ashes.

(FWIW - I've not seen any harm to acid lovers from adding ashes. However, my soil is already acidic so perhaps I've just moved it temporarily in the direction of neutral.)

If you can get barn material - well-rotted, and deep litter from a local chicken keeper, both of those do well when added to aged humus.

Hope you have a great garden this year.

Just as a side note: Mulch is any material that is applied to the surface of your soil to keep your soil moist, serve as a weed barrier, keep soil roots cool. It's especially nice if the mulch is something that will break down eventually and fertilize your soil, but mulches come in all shapes---slow to break down woody mulches, impossible to break down plastic and gravel mulches.

If you mix mulch into your garden soil, it is no longer mulch, it's a soil amendment.

The stuff you're describing sound fabulous. It will only be called mulch if you apply it to the surface of your soil. Otherwise, it's compost (and fine sounding compost indeed). It gets confusing because compost is often used as mulch----applied to the soil surface.

Anyway, I'd agree with vetivert, except if your soil is alkaline, you do not want to use woodash, and even if your soil is acidic, you should apply it very lightly.