Whisk garlic, lemon juice, mustard, vinegar, and light sprinkling of salt and pepper in Pyrex measuring cup. Slowly whisk in olive oil to make a thick dressing; set aside.

Meanwhile, bring 2 quarts of water and 1 tablespoon of salt to a boil in a large pot. Add pasta and cook until approaching al denté, about 10 minutes (follow package instructions). Add seafood to pasta and continue to cook until seafood is just opaque, a minute or two more. Drain (do not run under cold water) and pour onto a baking sheet to cool. Just before serving, mix pasta and seafood, tomatoes, roasted peppers, cheese, and oregano in a large bowl. Add dressing, toss to coat, and serve.

Note: This may be prepared in advance, chilled, and served cold if desired.