You use Herbalism. Have the skill, press the button, have the ingredients and bang, available recipes are there in bold.
Bodahn has infinite amounts of concentrator agents and bottles and a few other things. Deep Mushrooms from Ruck in Deep Roads, Elfroots from the Dalish, Lyrium from the Circle Tower... that's all I know off the top of my head. Recipes from various vendors, visit all of them.