Shrimp and Tuna Salad with Vinaigrette

2 tablespoons white wine vinegar

1 tablespoon lemon juice

1/2 cup olive oil

salt, to taste

pepper, to taste

2 - 6 tablespoons flat-leaf parsley, chopped, depending on your preference for the herb

500 grams shrimp, steamed and peeled

2 pieces tomatoes, seeded and diced

1 piece cucumber, peeled, seeded, and diced

1 can (184-gram) canned tuna in water, drained and flaked

lemon, to serve