- On the coarse side of a box grater grate the tomato into a bowl. The skin will peel away—discard. Grate the onion into the bowl as well and season with salt and pepper.
- Center coals in grill, light, and allow to reach 375 degrees. Place a 14-inch cast iron skillet over the coals and let sit for about a minute.
- In a separate small pot, pour stock and keep on the grill to stay warm.
- Add olive oil to the pan and add sofrito and let sauté about 5 minutes until the liquid has cooked out and the vegetables are beginning to break down. Add saffron, roasted pepper, and garlic and cook for one minute.
- Add rice to pan and stir for one minute. Add one quart stock and season to taste. Let this cook for about 15 minutes stirring occasionally. Do not stir during the last few minutes of cooking this will help form the soccarat (the crispy edges of rice that add a great texture). Check to see if the rice has absorbed most of the liquid. If it has absorbed too much add another cup that you have on hand and add wine and stir one final time.
- Arrange clams around the outer edge of the pan followed by the mussels and shrimp. Let this cook with your grill lid closed for 5−8 minutes. Remove the pan from the grill and let rest 10 minutes. If the shrimp are not fully cooked you can cover the pan with aluminum foil to finish cooking the shrimp