Materials are found everywhere in Hyrule: from plants and mushrooms to monster parts and ore. These are primarily used for cooking meals and brewing elixirs, which provide healing, stamina recovery, and temporary buffs.
Cooking:
Combine up to five ingredients in a cooking pot (found at stables, villages, or created with wood and flint). Experiment with combinations. Adding 'Hearty' ingredients (e.g., Hearty Radish) grants full recovery plus bonus hearts. 'Endura' ingredients (e.g., Endura Carrot) restore and temporarily extend stamina. 'Mighty' ingredients boost attack, 'Tough' boost defense, 'Sneaky' boost stealth, etc.
Elixirs:
Combine a monster part with an insect or critter (e.g., a Fireproof Lizard and a Bokoblin Horn). Elixirs provide specific buffs (e.g., Fireproof Elixir, Hasty Elixir) but do not heal. The quality of the monster part affects the duration of the buff.
Always carry several ingredients and cooked dishes to be prepared for any situation.