Tempura spring onions with onion purée

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This glorious tempura spring onion recipe is served with a rich onion purée and powder made from dried onions, which creates an incredibly intense seasoning for the dish. Rather than use a dehydrator, head chef at Root Rob Howell, who devised this recipe, uses their kitchen's plate warmers to get the onions super crispy for the powder. If you'd rather give the powder a miss, the crisp, sweet spring onions and onion purée are more than delicious enough on their own to make a stunning vegan starter.

First published in 2018




Spring onions

Onion powder

Onion purée

  • 8 onions, finely sliced
  • 100ml of rapeseed oil
  • 1 pinch of xanthan gum
  • 20ml of sherry vinegar
  • salt

Tempura batter

  • 70g of plain flour
  • 30g of cornflour
  • 1 tsp bicarbonate of soda
  • 1 tsp baking powder
  • ice cubes
  • sparkling water
  • rapeseed oil, for deep-frying


  • Blender
  • Dehydrator


For the onion powder, evenly spread the sliced onions in large trays and place in a dehydrator for approx. 24–48 hours until brittle and fully dried – some of the onions will go quite dark, which is great for the flavour. Place in a food processor and blitz with a small amount of sea salt. Push through a fine sieve and reserve the powder in a sealed container
To make the onion purée, add the oil to a pan and place over a low-medium heat. Add the onions to the pan and add a generous pinch of salt – this will help them to break down. Cook low and slow for approximately 45–60 minutes to give beautifully golden, sweet onions. Once cooked, transfer to a blender and blitz to a smooth purée, adding a little water if necessary to loosen it a little. Finish by blending in a pinch of xanthan gum, salt if needed, and the sherry vinegar
Prepare the spring onions by trimming the tops and the bottoms, but try not to take too much away. Wash thoroughly, then blanch for 2–3 minutes, holding the onions upright in the pan with the bulb at the bottom to ensure they cook evenly. Place straight into iced water to cool
To make the batter, whisk together all the ingredients in a bowl, stirring in enough water to give a nice, thin batter. Add the ice cubes to the batter to keep it nice and cold – at the restaurant they add crushed ice to the batter, which they add to the fryer. This makes the fryer bubble furiously, which creates a super-crispy, bubbly coating, but is definitely not advisable in a home kitchen as it might prove quite dangerous! Chilling the batter with ice cubes before coating the onions will suffice, as the colder the batter, the better
Preheat a deep-fryer or deep pan of oil to 180°C
Coat the onions in the batter and allow some to drip off – you are not looking for a thick consistency here. Place the battered onions in the fryer for approximately 90 seconds until the batter is nice and crisp. Remove from the fryer and drain on kitchen paper or a J-cloth before seasoning well with salt and the onion powder
To serve, place a few onions on each plate and add a dollop of the purée to act as a dip. Finish with a sprinkling of the onion powder to serve
First published in 2018

Rob Howell is the head chef at Root, a veg-centric restaurant in Bristol's Wapping Wharf.

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