To unlock this achievement, you must learn 50 new recipes. Other than randomly generated loot from chests, caches, corpses and mobs, you can purchase all recipes from their respective vendors. Cooking recipes can be acquired from chefs, weapons and armour recipes from blacksmiths, alchemy recipes from alchemists, and all other general recipes from shopkeepers and merchants. All you need is enough money to purchase them, and once you have learnt 50, the achievement will unlock. Note that you will not be able to learn the same recipes on new characters and have them count toward the achievement.