Steam the clams in very little water until they open. Discard any that do not open and set the clams aside. Reserve the cooking liquid, being careful to keep any sand the clams expel at the bottom of the pot.
Sauté the rice in the olive oil until golden brown. Add the onion, green pepper, garlic and linguiça. Cook for 5 minutes, stirring occasionally. Break the tomatoes up with the back of a spoon, saving the juice (to use if needed when cooking the rice), and add to the rice mixture. Cook over a low flame until the rice is soft. Add some of the reserved clam juice when necessary. Remove the clams from their shells, keeping 8 to 10 in the shells for garnish. Add the clams and saffron. Mix well and serve with Portuguese bread.