Cut the red pepper, cucumber and red onion into bite-sized pieces; halve the cherry tomatoes; roughly chop the parsley.
Drain and rinse the chickpeas, cannellini beans and kidney beans in a colander under cold running water.
In a small bowl, whisk together the extra virgin olive oil, red wine vinegar, Dijon mustard, minced garlic, salt and black pepper until the dressing is emulsified.
In a large bowl, combine the drained chickpeas, cannellini beans and kidney beans with the diced pepper, cucumber and red onion, halved cherry tomatoes and chopped parsley.
Pour the dressing over the salad and gently toss to coat everything evenly.
Cover and chill in the fridge for at least 30 minutes before serving.