Remove and discard fat and tendons from heart.
Cut heart in 1 inch pieces, cover with cold water, add vinegar, soak for 3 to 4 hours.
Drain; place in 2 1/2 quart casserole.
Cover, cook in Radarange oven 8 minutes.
Add onions and broth; cook in oven 15 minutes, stirring 3 times.
Mix flour with cold water to make a paste, stir in soy sauce and seasonings.
Stir into cooked mixture; add celery; cover, cook in oven 3 minutes.
Add bean sprouts; cook in oven 1 minute to heat through.