In a bowl, toss the meat or fish with the sherry, red pepper, and 2 teaspoons of the cornstarch. In a measuring cup, combine the orange juice, chicken broth, soy sauce, sugar, and the remaining cornstarch.
In a large nonstick skillet or wok, heat the oil over medium-high heat. Add the orange zest and let it sizzle for 1 minute. Add the onion and the meat or fish and cook, stirring, until cooked through, 2 to 5 minutes. Add the orange-juice mixture and broccoli. Simmer 5 minutes or until the broccoli is tender.