Heat oil in a large saucepan over medium-high heat. Add onion, garlic and celery, cook stirring regularly, for 4-5 minutes or until onion has softened.
Stir in dill, coriander, parsley, butter beans, vegetable stock and water, bring to the boil then reduce heat to low. Simmer for 4-5 minutes, or until vegetables are tender.
Remove from the heat and use a stick blender to blend until smooth. Add the yoghurt and lemon juice and stir until well combined.
Divide soup between 4 bowls and garnish with reserved dill and cracked black pepper before serving.