In a saucepan of boiling salted water, cover and cook rice until tender and most of the rice is split, 30–45 minutes. Drain and let cool.
In a large bowl, whisk oil, vinegar, honey, mustard and salt; stir in shallots and let stand 5 minutes. Fold in rice, apple, celery, cheese, cranberries and sunflower seeds, tossing to coat.