Heat oil in 2-quart saucepot over medium-high heat and cook mushrooms, onion and red pepper, stirring occasionally, until tender, about 4 minutes. Stir in rice and cook until golden, 1 minute.
Stir in water and Knorr® Homestyle Stock - Beef. Bring to a boil over high heat; stir.
Reduce heat to low and simmer covered 15 minutes. Stir in peas and continue cooking covered until rice is tender and water is absorbed, about 5 minutes. Sprinkle, if desired, with chopped fresh parsley.