At home, place first 4 ingredients in a heavy-duty zip-top plastic bag. Combine vinegar and next 8 ingredients (vinegar through bay leaf) in a heavy-duty zip-top plastic bag. Place in cooler or backpack.
At campsite, heat oil in a large Dutch oven over hot coals (or in a Dutch oven over medium-high heat if at home). Add onion, bell pepper, celery, and garlic; sauté 8 minutes or until tender. Add vinegar mixture, kidney beans, tomatoes, and pinto beans; cook 20 minutes, stirring often. Discard bay leaf. Stir in cashews.