Heat the olive oil in a large soup pot over medium heat. Add the chopped onion and sauté until soft and translucent. Add the garlic and continue cooking until fragrant. Stir in the crushed red pepper, the wine and the diced tomatoes. Turn up the heat and bring the liquid to a quick boil. Add the mussels, all at once and cover immediately. Cook for about 3 minutes, shaking the pan every 30 seconds or so to redistribute the mussels. Uncover and check to see if the majority of the mussels have opened. If not, cover again and continue to steam for another minute or so.
Once the mussels have opened, quickly transfer them to a serving bowl. Stir the breadcrumbs into the still simmering pan juices to thicken them slightly, add the parsley and pour the mixture over the mussels.
Tips for Making This Recipe
To clean the mussels, scrub the outer shell lightly with a soft brush, rinse thoroughly and drain. Trim away any tough brown fibers (known as the "beard") with a pair of kitchen shears. Keep refrigerated at all times.