Potions and Elixirs are brewed in any DESK (Alchemy table) at campsites or save points in the game. There are a total of 8 types you can craft once you unlock them by finding the recipe:
Healing Potion
Mana Potion
Stamina Potion
Mystery Potion
Sharpshooter Elixir
Bladedancer Elixir
Stoneskin Elixir
Conjurers Elixir
Once you craft 10 of these in a playthrough you will unlock this achievement.
My favorite item farming locations In order of Appearance:
1- Hunted Crags: plenty barrels that are quick to burn and collect and Wailing Spirits are easy enough to avoid. Leave the area and return to rinse and repeat.
2-Haunted Cliffs North-west most cave: plenty barrels together to rinse and repeat at leisure, no wailing spirits to dodge here.
3- The tower has a dozen barrels per floor and you can kind of go up and down at leisure burning away (or just come back and forth in 1st and 2nd floor).
After beating the final boss, you can continue to play and mop up any achievements you may have overlooked but if you start a new play-through, the potion brewing will have to start from scratch.