Molho A Campanha (Country Salsa)

Ingredients

• 3 tablespoons red wine vinegar, or more to taste
• Coarse salt (kosher or sea) and freshly ground black pepper
• 1/2 green bell pepper, cored, seeded, and cut into 1/4-inch dice
• 1/2 red bell pepper, cored, seeded, and cut into 1/4-inch dice
• 1/2 yellow bell pepper, cored, seeded, and cut into 1/4-inch dice
• 1 large ripe tomato, cut into 1/4-inch dice
• 1/2 sweet onion, cut into 1/4-inch dice
• 3 tablespoons finely chopped fresh flat-leaf parsley
• 3 tablespoons vegetable oil