Pick the leaves from the stalks of the parsley mint and dill and combine with the capers & garlic. Blend together in a food processor, adding lemon juice and olive oil to create a thick herby dressing, season to taste.
Prepare the vegetables by podding the beans and peas if necessary and snapping off any tough ends of the asparagus.
Set a large heavy based frying pan on the stove to heat up. Season the steaks with plenty of olive oil, sea salt and ground black pepper. When the pan is hot add the steaks and cook for 2 minutes on each side for rare. When the steaks have finished cooking add 50g of the butter set aside to rest.
Whilst the steaks are resting cook the veg. Preheat a wide saute on the stove, add the second amount of butter and a 3-4 tbsp of water until boiling. Add the beans to the pan and cook for 1 minute before adding the asparagus and peas. Bubble the veg away on the stove until the asparagus, peas and beans are tender and bright green.
Slice the sirloin steaks with a sharp knife and season the slices with a touch more salt and pepper.
Scatter the vegetables on a wide platter alongside the slices of sirloin. Dress the salad with the herby sauce and finish with a scattering of the fennel fronds and some chive flowers if you have them to hand.