Cook the beans following the instructions on the bag or place in a slow cooker with 6 cups of water and cook on low for 8 hours or overnight. Strain, then cool the beans and place in a large mixing bowl. Mix in the chopped red onion, plum tomato, chopped cucumber, and minced garlic. In the beaker of a blender combine the parsley, basil, Dijon mustard, sugar, kosher salt, red wine vinegar, olive oil, and water. Cover and blend on high for 45 seconds or until herbs are completely puréed. Toss the dressing with the beans and vegetables. Taste and adjust seasonings with salt or sugar if needed. Serve over a bed of mixed greens or baby arugula.