Spring onion soup with green oil

Method

1. Set aside 3 spring onions and slice the rest. Heat the olive oil in a pan and fry the sliced spring onions, garlic, a pinch of salt and the mustard for 5 minutes. Add the potato, cook for 4 minutes, stirring often, then pour in the stock and simmer for 20 minutes.
2. Meanwhile, halve the reserved spring onions. Roughly chop the green parts, then whizz in a small blender with 100ml veg oil until bright green. Pour into a sieve set over a small bowl and leave to drip through.
3. Shred the white parts into fine strands. Pour enough veg oil into a small pan to cover the base, heat until shimmering hot, then fry the spring onion whites until golden and crisp. Drain on kitchen paper and season with salt.
4. When the soup is ready, add the parsley, take off the heat and whizz with a stick blender until smooth, adding milk or stock to thin it out. Season to taste with salt, pepper and lemon juice. Serve with a drizzle of the green oil and the spring onion ‘hay’.