Fill a large saucepan (with a lid) with water about 3/4 way up. Bring the water to a boil and add about 1 teaspoon kosher salt. Stir in the rice and cook about 5 minutes few than according to the package times.
Drain the rice well in a fine mesh colander. Transfer the rice back to the saucepan and put the lid on tightly. Let the rice rest in the pot for 10 minutes. (This actually steams the rice).
Transfer the rice to a large (wide) bowl and spread it out in an even layer. Set aside for the rice to cool and dry completely.
FOR THE RICE SALAD:
In a large bowl combine the bell peppers, red onion and scallions. Mix to combine.
Wash the kale leaves and spin in a salad spinner. Transfer to a large cutting board and massage the kale for 2-3 minutes with your hands until it's very soft and fragrant and the leaves have turned a dark, bright green.
Bunch the kale tightly into a ball and use a sharp knife to cut very thin slices of the kale. Add the kale to the pepper mixture.
Rinse and drain the black beans in a colander, running fresh water over them to remove any bean liquid. Let the beans rest for a minute or so to drain completely. Add the beans to the pepper mixture and toss gently.
FOR THE DRESSING:
In a medium bowl or 2-cup glass measuring cup combine the garlic, dijon mustard, lime zest, lime juice, kosher salt, black pepper and cumin. Whisk well to combine. Slowly pour the olive oil into the dressing, whisking constantly so that the dressing emulsifies.
ASSEMBLE THE SALAD:
Add the bell pepper mixture to the cooled and dry rice and toss well to combine.
Add the dressing a little at a time, tossing after each addition just until the salad is well dressed but not sopping wet. You don't want to overdress the salad. (Any leftover dressing can be used on salads or to dress steamed vegetables).
Serve at room temperature or chilled. Salad can be made a day or two ahead of time.