The wild larder that grows itself.
Scotland has more edible seaweed per mile of coast than almost anywhere on earth, and until very recently we largely ignored it. Dulse, laver, sea lettuce, kelp — they're all free, wild, and taste like the sea concentrated into a leaf. Learn to use one and you'll never buy stock cubes again.
Foraged from clean rocky shores at low tide, or bought dried from Scottish suppliers like Mara. Never take from stagnant pools or near sewage outfalls.