Molho à Campanha

Ingredients

• 3 tablespoons red wine vinegar, or more as needed
• Coarse salt (sea or kosher)
• Freshly ground black pepper
• 1/2 each red, green, and yellow bell peppers, cored and diced
• 1 serrano pepper, cored and minced (optional)
• 1/2 sweet onion, peeled and diced
• 3 tablespoons chopped fresh flat-leaf parsley or cilantro
• 3 tablespoons extra virgin olive oil, or more as needed