Recipes are quite important in Hyrule Warriors: Age of Calamity. You can chow down on some nice food before missions, getting some buffs that will make your life a bit easier as you play through the quest.
To get recipes, you will need to complete small node quests marked on the map by a cooking pot. Most of these will require you to hand in some form of resource that you can farm while play through missions. This can actually be the most awkward part and might require you to grind some missions a few times to get everything you need.
You can also get recipes as rewards for some quests. On the main map screen, use the shoulder button to navigate to Quests, and then Cooking. Here, you will see a full list of cooking quests that you have opened up the game, whether they are completed or not, and their requirements. It is an easy way to keep tabs on how much you may still need to do to get access to everything.
To actually use a recipe, you need to be just about to load into a mission. Click on the cooking options before you load in, and you will see a list of recipes you have and the benefits that they give you. Some of them can increase your movement speed, increase your damage, or reduce incoming damage, among other benefits. They can give you an edge in tougher missions, so don’t forget about them.