Combine 3 tbsp butter, 1/2 tsp dry mustard, 1 tsp thyme, 1/2 tsp salt, 1/2 tsp freshly ground black pepper, 1 tsp freshly grated lemon zest and a a dash of lemon juice in a saucepan.
Cook over a low flame, until the butter is melted.
Adjust the seasoning to taste.
Split 3 broilers and sprinkle them generously with salt, pepper and thyme.
Put the broiler halves in a hinged double broiler.
Broil them skin-side up about 2 inches from the coals for 10 minutes.
Stick half a lemon on the end of a long fork.
Use it as a dipper and baste the chickens frequently with the prepared sauce.
Turn the chickens.
Broil them for 10 minutes longer until the skin is evenly browned and the meat is thoroughly cooked.