How to Make It
In a small saucepan, cover the lima beans with water and bring to a boil. Add a pinch of salt, cover and simmer over moderately low heat until tender, about 10 minutes. Drain and let cool.
Puree the lima beans in a mini food processor. Add the butter, chives, parsley and dill and process until smooth. Season with salt and hot sauce.
Light a grill. Rub the swordfish steaks with olive oil and season with salt and pepper. Grill the fish over moderately high heat until nicely browned outside and just opaque throughout, about 4 minutes per side. Top the fish with the lima bean butter and serve right away.