In a large stock pot over high heat add 2 tablespoons oil. Add the chicken thighs and ham hocks and brown thighs on both sides. Remove chicken to a plate, leaving the ham hocks in the pot. Add to pot 1 cup of onions, celery, carrots and garlic and cook for 5 to 7 minutes. Deglaze with white wine and reduce by half. Next add the seafood stock, saffron and 2 quarts of water and let simmer for 2 hours or until reduced by half. When stock is finished simmering, strain and hold stock on low heat.
In a large saute pan or paella pan add the remaining 2 tablespoons oil, chorizo, red bell pepper and the remaining 1 cup onion, cook until the onions are translucent, but do not brown. Add rice, salt and pepper to pan and saute until all grains of rice are coated with oil of the pan. Form rice around the pan so it is level, next add 1 cup of broth at a time to the rice; do not stir the rice. When rice is al dente, or 3/4 of the way of being fully cooked, add chicken thighs, shrimp, scallops, mussels, and clams. Bury the seafood items in the rice so they will cook.
Add final cup of broth and cover entire pan tightly with another pan or lid. Let sit off heat for 10 to 15 minutes or until seafood is cooked.
Garnish with scallions and Roma tomatoes