Quinoa is an ancient variety of grain from South America that has become fashionable for its high protein content and gluten-free properties. It is available from health shops at a fairly hefty price. You can, if you want, use sushi rice instead.Ingredients60g fresh root ginger, peeled and very finely slicedSalt1 small piece raw beetroot (it gives the ginger a lovely pink hue)Tezu (vinegar pickling liquid)60ml (4 tbsp) brown rice vinegar30ml (2 tbsp) water10ml (2 tsp) runny honey or light agave10ml (2 tsp) sea saltQuinoa sushi300g (1 cups) quinoa750ml (3 cups) waterNori sheetsVegetables, such as mange tout, carrot and red cabbage, blanched and cut into long, thin stripsAvocado and cucumber, cut into thin strips200g poached salmon, tuna or peeled prawnsToasted sesame seeds, to serveMethodSprinkle the ginger with salt, toss to coat, and stand for 30 minutes. Using your hands, squeeze out the ginger over the sink, then place in a colander, rinse well and squeeze out again until as dry as possible. Place in a glass jar with the beetroot. Whisk together all the tezu ingredients. Set half the liquid aside to dress the quinoa. Pour the other half into the jar, making sure the ginger is submerged. Seal and set aside to marinate.Rinse quinoa well and drain. Place in a pot with the water. Bring to the boil, reduce heat, cover and simmer for 15-20 minutes until the water has been absorbed. Don't stir. Transfer the cooked quinoa to a large bowl and cool slightly. Fold in the reserved tezu and adjust seasoning - it should have a distinct sweet acidity without being overpowering. Cover loosely with a towel and allow to cool completely.Place a sushi mat or piece of plastic wrap on a clean cutting board with the slats running horizontally. Place a nori sheet shiny side down on the mat, 2cm from the edge closest to you. Use wet hands to spread a thin layer of quinoa evenly over the nori sheet, leaving a 3cm-wide border along the edge furthest from you.Arrange the vegetables and seafood across the centre of the quinoa. Use your thumbs and forefingers to pick up the edge of the mat closest to you. Use your other fingers to hold the filling in place while rolling the mat up around it. Gently pull the mat as you go to create a firm roll. Continue rolling until all the quinoa is neatly rolled in the nori. Shape your hands around the mat to gently tighten the roll, then cut into pieces with a sharp, wet knife. Repeat for remaining nori sheets and filling.Arrange on a platter, sprinkle with sesame seeds and serve with pickled ginger. Extra ginger can be refrigerated for 2 weeks...