What's for Dinner?
During the day, talk to Kiana at Lurelin Village. She is Sebasto's wife. She wants to cook dinner for the family but is missing key ingredients. She needs Goat Butter and Hearty Blueshell Snail. You can buy Goat Butter from general stores all over Hyrule, and you can gather the snails from the beach right in the village. They glow at night, so if you are having trouble finding them, wait for the sun to set.
Give them both to her when you're ready for a purple Rupee worth 50 Rupees. You have to make sure you do so before 5:00 PM or else she will have already made dinner. She will also give you Seafood Paella, the dish she made with your ingredients. It heals for a lot of hearts so it's very valuable.