It's a seafood salad - shellfish vinaigrette. We haven't got it on our site as it's not a specifically Dominican recipe, although it is served in DR restaurants. Basically you mix any type or combination of shellfish with chopped onion, tomato, olive oil, vinegar and salt.
Similar ingredients but not the same process - with ceviche you 'cook' the raw seafood in lemon juice overnight. With salpicon you add the shellfish once it's been cooked the normal way.