Supersoil

KIS, build-a-soil, and Nature’s Living Soil all have supersoil concentrates that you mix with an organic soil of your choice. I’ve used Nature’s Living Soil (Amazon) a bunch of times when I was starting out with Organics. It is easy and I got good results, but like @smoke24 said, I also experienced N excess in a lot of those grows. I also agree that you should start with a good organic potting soil first. Roots Organic Original always worked for me. Never burned any seedlings and it feeds your plant for the first few weeks. After that, you just top dress every 3-4 weeks with an organic dry fertilizer or mixture of organic amendments. Personally, I’ve had good results top dressing with a mixture of Down to Earth All Purpose and Dr. Earth Flower Girl, along with some earthworm castings.

Super soils will still needs to be amended with some form of nutrients every 3 weeks or so. I have used autoflower supersoil concentrate (amazon), with good results. You mix in some into the bottom 3rd of your pot, then fill the rest with regular potting soil. When the plants roots grow enough they will hit that nurtient dense bottom 3rd of the pot and be good to go for 3-4 weeks. After that you can top dress with some more of the super soil concentrate. Its not a bad way to go, but I find that the plants get too much nitrogen....not enough to cause serious symptoms, but enough to darken the leaves more than they should be. The safest bet would be to use good potting soil, and then amend with a good organic fertilizer after 4 weeks, and then you should only have to amend every 3 or so weeks after the initial feeding. Happy growing!

Compost. It's usually highly nutritious.. - Add some chicken poop to it and you likely won't need to use fertilizers. Can use nettle soup in your water for extra effect. It's not exactly "super soil" but it's in that league.