Watercress & beef noodle soup

Instructions

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1. 1 Season the steak well on both sides using salt. Set aside at room temperature. Bash the lemongrass stalk using the flat side of a knife blade, then cut in half. Finely slice the shallots and finely grate the ginger. Pick the leaves from the coriander and finely chop the stalks.
2. 2 Heat the oil in a saucepan over a medium heat and cook the shallots, ginger, star anise and coriander seeds for 3-4 mins until softened and fragrant. Stir in the lemongrass, coriander stalks, stock, fish sauce and sugar. Bring to a simmer and cook for 10 mins.
3. 3 Meanwhile, put the steak in a large, dry non-stick frying pan. Set over a medium-high heat and hold fat-side down, using tongs. Cook for 4-5 mins until the fat renders and turns golden. Set the steak flat in the pan and cook undisturbed for 2-3 mins until browned, then flip and cook for a further 2-3 mins until medium rare. Remove to a plate and leave to rest. Add a generous splash of water to the pan and, still over the heat, scrape up any browned bits. Pour this into the beef stock.
4. 4 Cook the noodles following pack instructions. Rinse well to prevent sticking, then divide between bowls. Roughly chop the watercress and add to the broth. Cook for 1 min, then season to taste.
5. 5 Juice the lime. Remove the lemongrass and star anise from the broth using a slotted spoon. Pour in any steak resting juices. Season the broth to taste using the lime juice and some salt and pepper. Slice the steak thinly against the grain, then arrange over the noodles and ladle over the stock. Scatter over the coriander leaves.