The stuffing for these quahogs (hard-shell clams) includeschorizo, a spicy pork sausage, and gives a nod to a classicPortuguese dish, porco com ameijoas (pork with clams).
Preheat oven to 300 degrees. Place cubed bread on a rimmed baking sheet. Toast until dry, about 15 minutes. Set aside.
In a saute pan set over medium-high heat, cook chorizo, stirring occasionally, until fat is rendered and chorizo is lightly browned, about 4 minutes. Using a slotted spoon, remove chorizo from fat, and transfer to a paper-towel-lined plate. Blot dry, and set aside.
Under running water, scrub clams clean. Place in a large stockpot, and add 2/3 cup water. Cover pot, and place over high heat. Steam until all clams have opened, about 10 to 15 minutes. Remove clams from pot, discarding any that do not open; strain broth through a paper-towel-lined fine strainer; set aside.
Remove meat from shells. Chop into 1/4-inch pieces; set aside. Separate shells into halves; clean them thoroughly by boiling in a large pot of water for 5 minutes. Remove shells from pot; let cool.
In a large saute pan set over medium heat, warm olive oil. Cook garlic, onions, and red-pepper flakes, stirring, until onions are soft and translucent, about 8 minutes. Let cool to room temperature.
In a large mixing bowl, beat 1 cup reserved clam broth into eggs. Add onion mixture, clams, chorizo, and herbs; toss well. Add bread cubes. Fold together until just mixed. Season with pepper.
Heat grill. Fill each clam shell with stuffing, about 1/4 to 1/3 cup filling per shell. Dot top of each filled shell with butter. Place quahogs, stuffing side up, on grill; cook, covered, for 10 minutes. Transfer to a serving plate; serve warm.
Quahogs are found mainly off the eastern coast of the United States; steamer clams may be used instead.