Heat the olive oil in a saucepan over medium heat. Add the chopped onion and garlic and gently fry for 3–4 minutes until soft.
Stir in the oregano and chilli flakes (if using).
Add the diced carrot and cook for 1–2 minutes.
Pour in the vegetable stock and bring to a boil. Cook for 5 minutes.
Add the green peas and cook for an additional 5 minutes until the vegetables are tender.
Turn off the heat and stir in the rocket leaves. Use a hand-held blender to blitz the soup until smooth and silky.
Season with lemon juice to taste and serve, garnished with extra rocket leaves if desired.