Italian Party Flank Steak

Name: Italian Party Flank Steak
Ingredients: 1/4 cup olive oil; 1/4 cup red-wine vinegar; 2 coves of garlic, finely chopped; 2 tablespoons chopped parsley; 1/4 teaspoon coarse black pepper; 1 flank steak (3/4 in thick, about 1 1/4 lbs), butterflied; 2 red bell peppers; 3 tablespoons chopped parsley; 6 to 8 thin slices of prosciutto or other cured ham; 24 medium sized fresh basil leaves; 2 tablespoons grated Parmesan cheese; Freshly ground pepper to taste; 1 bunch watercress for garnish; Kitchen string