Heat oil in 12-inch nonstick skillet over medium-high heat. Cook onion, garlic, bell peppers and mushrooms in oil 3 to 5 minutes, stirring frequently, until onions are crisp-tender. Stir in rice. Cook 1 minute, stirring constantly.
Stir in 1/2 cup of the broth. Cook, stir-ring constantly, until liquid is completely absorbed. Stir in an additional 1/2 cup broth. Continue cooking about 20 minutes, adding broth 1/2 cup at a time after previous additions have been absorbed and stirring constantly, until rice is creamy and just tender; remove from heat. Stir in remaining ingredients. Let stand 1 minute.