Blanch beans in salted water 4-5 minutes (until tender, but still a little crisp).
Meanwhile, melt 4 T butter (half a stick). Add zest and juice of one lime (or lemon), 1 1/2 t sea salt, 1 1/2 t dill weed, 1 t cracked black pepper, 1 t parsley, 1 t grated fresh ginger, 1/2 t ground mustard. Combine.
Drain beans and gently toss with butter mixture. Serve immediately. The last time I made these I used haricots verts (French String Beans), lemon & garlic.