Al Dente's Shellfish Paella in a Clay Casserole

Source: Al Dente's, Scottsdale, Arizona

1/3 cup olive oil
2 pounds white onions
2 1/2 pounds tomatoes
2 pounds green peppers
16 manila clams
8 mussels
1 pound squid
8 jumbo shrimp
1/2 pound Spanish chistorra
1 pound chicken
1 1/2 cups short rice
Touch of saffron
2 liters chicken broth

Heat oil in a shallow clay casserole or large skillet. Add onions and saut