''Pass the salt" is a tricky request these days. Pink crystals or grey? Truffle or Christmas tree flavour? Crunchy flakes or lustrous pearls? From the sea or the earth? Or maybe you'd like to grate your own? Salt has never been so abundant in so many different guises.Luxury food retailers are reporting "unprecedented" demand for gourmet and flavoured salt lately.Best-sellers include a shiny hunk of pink Himalayan salt; bourbon flavoured smoked salt; and a truffle salt from Umbria. Other posh salt flying off the shelves includes umami, Christmas Tree, porcini, chilli and Fleur de Sel.The trend is being driven by a return to cooking from scratch, with many home cooks following the lead of well-known chefs experimenting with unusual salts.At his NOPI restaurant, Yotam Ottolenghi pairs baby chicken with lemon myrtle salt and chilli jam, while Dan Doherty, executive chef at London's Duck & Waffle restaurant, serves his food on a slab of pink Himalayan salt."The idea is to use your fingers, give it a little rub to pick up the salt and you're good to go," he says.Mineral rich, deeply flavourful crystals can be sprinkled over salads, cooked meat and fish, as well as sweet things like chocolate, caramel, brownies and fresh fruit. Doherty always uses traditional Maldon salt, the famous natural sea salt from Essex, and says he can instantly tell if a dish has been seasoned with inferior table salt (sourced from mines, not the sea, and highly refined so most of the minerals are removed).Halen Môn sea salt, made from seawater surrounding the isle of Anglesey in Wales, is fast becoming the go-to gourmet salt for chefs including Heston Blumenthal. Alison Lea-Wilson, co-founder of Halen Môn (the Welsh translation of Anglesey Salt), says there was no market for artisan salt when she and husband David started the company almost 20 years ago.Now, the crunchy, sparkly flakes have Protected Designation of Origin status like Champagne and Parma Ham.Best flavoured and gourmet saltsHalen Mon - harvested, rinsed, dried and packed by hand from water around the isle of Anglesey in north Wales.Lake Assal salt pearls - naturally occurring salt spheres from Lake Assal in the Danakil Desert, Africa.Fleur de Sel - literally ''flower of salt", this has been gathered in Brittany since the 7th century. Prized for its delicate flavour, the flakes are fine and contain a high concentration of minerals.Hawaiian black lava salt - collected from pools formed naturally from lava flows, the charcoal-coloured crystals have smoky sweet notes.Himalayan salt - naturally occurring pink crystals from the Himalayan Mountains in Pakistan, once reserved for royalty.Murray River Salt - light and delicate peach coloured flakes from the Murray River basin in Australia.Kala namak - also known as Himalayan black salt, the dark purple-black crystals have a sulphurous/smoky flavour that works well in Indian food...