Drain the beans. Rinse the chickpeas and navy beans under cold water, then drain them thoroughly. Drain the corn well, too. Letting excess water drip off helps prevent a watery salad.
Prepare the vegetables. Dice the cucumbers and bell peppers, finely chop the red onion, halve the cherry tomatoes, slice the olives, and chop the parsley and mint.
Whisk the vinaigrette. In a small bowl, whisk together the olive oil, lemon juice, lemon zest, honey, Dijon mustard, garlic, oregano, and salt until combined.
Combine the salad. Add the chickpeas, navy beans, corn, tomatoes, cucumbers, bell peppers, red onion, olives, feta, parsley, and mint to a large bowl.
Add the dressing. Pour the lemon-Dijon vinaigrette over the salad. Toss gently until everything is evenly coated, taking care not to mash the softer beans or feta.
Taste and serve. Let the salad sit for about 10 minutes if time allows, then taste and adjust the salt or add a squeeze of fresh lemon as needed. Serve immediately or cover and refrigerate for later.
