Cook both kinds of rice together according to brown rice package directions.

At the last 5 minutes of cooking the rice, when almost all of the liquid has evaporated, add the celery, carrots, and beans to the top of the pot. Cover again and continue cooing for 5 more minutes.

In the meantime, mix lemon juice, olive oil, and dill.

Mix dressing, rice, and beans together and add salt and pepper to taste. Serve immediately or cover and serve at room temperature.