Best bean salad

Ingredients

• 2 cups yellow beans , cut into 1-in. pieces
• 2 cups green beans , cut into 1-in. pieces
• 2 cups sugar snap peas , halved
• 1/3 cup extra-virgin olive or vegetable oil
• 1/3 cup red-wine vinegar
• 2 garlic cloves , minced
• 1 tbsp Dijon mustard
• 1 tbsp granulated sugar
• 1 1/2 tsp salt
• 1/2 tsp pepper
• 1/2 finely chopped red onion
• 1 540-mL can red kidney beans , drained and rinsed
• 1 398-mL can black-eyed peas , drained and rinsed
• 1 cup chopped parsley or cilantro