450g/1lb fresh spinach
175g/6oz lean fillet steak, cut into thin slices about 5cm (2 in) long
For the marinade
2 Scallion/Spring Onion Tails Sliced (Green end Only)
1 Tsp Garlic Oil
1 tbsp fish sauce
freshly ground black pepper
For the soup
1.2 litres/2 pints homemade chicken stock or good quality bought stock
2 tbsp fish sauce
1 tbsp lemon juice
1 tsp sugar
1 small, fresh red chilli, seeded and chopped
Remove the stalks from the spinach and wash the leaves well.
Blanch the leaves for a few seconds in a large pan of boiling water until they are just wilted, then drain well and refresh in cold water to prevent further cooking. Drain again, squeezing out excess water.
Combine the steak with the scallion, garlic oil, one tablespoon of the fish sauce and some freshly ground black pepper, then set aside. (The soup can be prepared in advance up to this point.)
Just before you are ready to eat, bring the chicken stock to a simmer in a saucepan and season it with the remaining fish sauce, the lemon juice, sugar and chilli.
Add the blanched spinach and stir in the beef and its marinade. Bring the soup back to simmering point, add a few grindings of freshly ground black pepper to taste and serve at once.