1-First Step: Mise en place and bean prep* Open and rinse the canned beans. Pour out the liquid from both the kidney beans and the cannellini beans, then rinse them thoroughly under cool running water. Drain well. Rinsing removes canning liquid and reduces sodium and metallic flavors.* Place the drained kidney beans, drained cannellini beans, and the thawed green beans into a large mixing bowl. Using thawed frozen green beans saves a step because they are already blanched; just be sure they are well drained so the dressing does not get watered down.

2-Second Step: Prepare the aromatics* Slice the red onion thinly. To mellow its sharpness, soak the slices in ice water for about five minutes. This softens the sulfur compounds that make onions bitey. After five minutes, drain and finely dice the onion before adding it to the beans.* Chop the fresh parsley and add it to the bean and onion mixture. The herb is small but adds an important fresh lift to the dish.

3-Third Step: Make the dressing* In a separate small bowl, whisk together the apple cider vinegar, sugar, olive oil, salt, freshly cracked black pepper, and Dijon mustard. Whisk vigorously until the sugar dissolves and the mustard helps create a temporary emulsion. Taste and adjust salt or sugar if needed.

4-Fourth Step: Combine and chill* Pour the dressing over the bean, onion, and parsley mixture. Stir gently but thoroughly to coat all the beans and vegetables with dressing.* Transfer the salad to the refrigerator and let it marinate for about 30 minutes. This step lets the vinegar and mustard flavors mellow and soak into the beans.* Before serving, stir again to redistribute any settled dressing. Taste and adjust salt or pepper as needed.

5-Final Step: Serving and portioning* Serve chilled or at cool room temperature as a side for barbecues, a potluck dish, or a protein-rich component in a packed lunch. This recipe yields about 6-8 servings as a side. For meal prep, portion into airtight containers for easy grab-and-go lunches.