Trim the French beans. Carefully drop them in a pan of boiling water and blanch for 3 mins. Drain and plunge into a bowl of ice cold water.
Halve the pepper. Scoop out and compost the seeds and the white pith. Finely dice the pepper. Chuck into a large serving bowl.
Pick the leaves from the chervil and coriander. Finely chop the stalks. Roughly chop the leaves. Add to the pepper. Peel and finely slice the onion. Peel and crush the garlic. Warm 1 tbsp oil in a frying pan over a low heat. Fry the onion for 10 mins till soft and starting to turn golden.
Add the garlic and 2 tsp coriander seeds. Fry for 2 mins till the seeds are popping and the pan
Tip in 1 tsp sugar and 1 tbsp red wine vinegar. Cook for 2-4 mins till the sugar has dissolved and
the onions are sticky.
Drain and rinse the butter beans. Drain the French beans. Add both beans to the pan. Cook for 3 mins till just heated through and coated in the fragrant onions.
Tip into the bowl with the pepper and herbs. Add 1 tbsp oil and toss together. Taste, season and serve.