Finely chop the onion, garlic and ginger. Peel and dice the potato.
Heat the olive oil in a large saucepan over a low heat. Add the onion and sauté gently for about 5 minutes, until softened.
Add the garlic, ginger and diced potato. Stir for a minute, then add the cumin and cook for a few seconds until fragrant.
Pour in the stock and bring to the boil. Simmer for about 5 minutes, or until the potato is almost tender.
Add the frozen peas and simmer for another 5 minutes, until tender.
Remove the pan from the heat and add the washed pea shoots. Blend with a hand-held blender until smooth.
Return the soup to a low heat and warm gently. Stir in the lemon juice and season to taste with salt and freshly ground black pepper.
Ladle into bowls and serve with a dollop of Greek yoghurt or crème fraîche and a few extra pea shoots.