All-Purpose Seasoning

I use Knorr Aromat, which is effectively MSG and salt with a bit of garlic and other token spices. Don't be fooled by the marketing, MSG is doing the heavy lifting, there's nothing perfectly balanced here.

Substitution

If you can get pure MSG, that's a perfect substitution combined with salt. You can also use Liquid Seasoning, although this will impart its own distinct flavour.