Salt water instead of plastics and pesticides; hand-woven baskets and mollusc permits in place of temperamental trolleys and credit cards - this is shopping at its best."I'm only wearing them to look professional," jokes Roushanna Gray, who runs Veld and Sea's sustainable foraging courses, when I ask if I can leave my slops in the car. Our group of about 20 walks down to the shimmering rock pools of Scarborough beach and for the next two hours we all slip comfortably into the role of modern hunter-gatherer as we harvest our coastal edibles in the food store of our ancestors.A steady flow of facts from our guide competes with the sound of the waves. Numbingly cold water sloshing around our legs, fingers combing the aptly named mermaid's hair or Cape cord weed (Chordariopsis capensis), feet wading through emerald-green forests of sea lettuce (Ulva spp), tongues first tentatively then more adventurously sampling the surprisingly varied tastes and textures of seaweed.I'm snacking on some deliciously crunchy branch-like segments of wrack (Brassicophycus brassicaeformis) when Roushanna holds up a handful of nori (Porphyra capensis) and with delight points out that the pink edges mean this one's female, soon to be transformed - with just a few minutes in the oven, and a bit of olive oil and salt - into tasty nori chips. Move over kale.Seaweed is one of the most nutrient-dense plants on the planet and there are more than 700 species of this superfood to be found along the South African coastline.Unlike mushrooms, for which making the distinction between the delicious and the deadly might be too much of a gamble for some, when it comes to seaweed it's difficult to go wrong because there is only one inedible species: acid weed (Chordariopsis capensis), a fan-shaped brown algae with serrated edges, that contains sulphuric acid. Fortunately, it grows only further out at sea, so by cutting only healthy-looking weeds still attached to rocks you can rest assured that your digestive tract will remain intact.Still not convinced? "Lick the leaf with the tip of your tongue, and if you can taste lemon drop it back in the water," said Roushanna.A coastal foraging session isn't complete without a few mussels - we pick only the invasive Mediterranean variety - and, if you're lucky, a beauty treatment.Carefully hoisting our edible treasures over the rocks, we hike through the sand to a beach cottage and settle down to the business of preparing our feast.In between chopping and slicing, we're all treated to a face mask made with the gooey filling of the unattractively swollen, calloused deadman's fingers (Splachnidium rugosum). Exfoliation follows, using the bizarre-looking tongue weed (Gigartina polycarpa).Then, with skin plump and glowing, we tuck into sushi balls that look like mini artworks, wrack coleslaw, mussels in a creamy garlic sauce and perfectly crisp nori chips.Come dessert, we are all in raptures over the chocolate ice cream: the unexpected addition of umami-rich seaweed transforms it into a treat so exquisite I can't help myself from sneaking into the kitchen for another spoonful.To learn more contact Roushanna at roushanna@hotmail.com and visit her blog (www.goodhopenursery.word-press.com) or Facebook page www.facebook.com/Veld-and-Sea to find out about foraging courses and pop-up events..