Trim the large leaves from the broccoli, and cut off any tough ends of lower stems. Rinse broccoli with cool water. Cut stems and florets into bite-size pieces. Cut stem ends from the mushrooms, and cut the mushrooms into 1/4-inch slices.
If the scallops are larger than 1 inch in diameter, cut each in half. Rinse with cool water, and pat dry with paper towels. Drain the roasted red peppers in a strainer; cut the red peppers into slices.
In a 2-quart saucepan, heat the rice and water to boiling over medium-high heat, stirring occasionally to prevent sticking. Once mixture is boiling, reduce heat just enough so mixture bubbles gently. Cover with lid; cook about 15 minutes or until rice is fluffy and tender. While the rice is cooking, continue with the recipe.
In a 3-quart saucepan or 12-inch skillet, melt the butter over medium heat. Add the mushrooms; cook about 5 minutes, stirring frequently, until tender when pierced with a fork.
Stir in the scallops, broccoli and roasted red peppers. Cook 3 to 4 minutes, stirring frequently, until scallops are white and opaque. Remove the saucepan from the heat.
Place the cornstarch in a medium bowl. Gradually stir the chicken broth into the cornstarch until the mixture is smooth. Stir the broth mixture and soy sauce into the scallop mixture. Heat to boiling over high heat, stirring constantly. Continue boiling 1 minute, stirring constantly. Serve over rice.