Bring 1 1/2 gallons of water to a rapid boil in a very large pot. Add salt and return to a boil. Add lobsters and cook 2 minutes. Carefully remove the lobsters from the pot and set in a dish or bowl filled with water and ice.

When lobsters have cooled, remove from the water, drain well and set on a cutting board. Cut each lobster in half lengthwise and remove the innards. Set lobsters on a plate and refrigerate until ready to cook. Lobster can be prepared to this point a few hours before needed.

When ready to cook, combine butter, cilantro, chilies, garlic and zest in a bowl. Preheat barbecue to medium-high (temperature should be about 400˚F in the chamber). Lightly brush each half lobster with oil.

Set lobster, flesh side down, with claws set above the hottest part of grill, and the tail portion, which cooks faster, near the cooler side. Cook lobster 3 minutes, until slightly charred.

Turn lobsters over. Now use a spoon to spread half the flavoured butter on the flesh and cavity of each lobster. Cook 3 minutes more. Now spread lobsters with remaining butter and cook 2 minutes more, until just cooked through. Set lobster on plates and serve with lime wedges for squeezing.