For Nam Prik, if using dried peppers, wear rubber gloves to cut open dried red chili peppers. Discard stems and seeds; cut up peppers. Place peppers in bowl and cover with boiling water. Let peppers stand for 45 minutes to 1 hour. Drain. In a blender container combine soaked peppers or crushed red pepper; the 1/4 cup water; the lemon juice; soy sauce; cooking oil; fish sauce or nuoc cham; and garlic cloves. Cover and blend until mixture is nearly smooth. Set aside.
Trim fat from beef. Partially freeze beef. Thinly slice across grain into bite-size strips. Set aside.
Pour cooking oil into a wok or large skillet. (Add more oil as necessary during cooking.) Preheat over medium-high heat. Stir-fry broccoli in hot oil for 3 to 4 minutes or until crisp-tender. Remove broccoli from the wok.
Add half of the beef to the hot wok. Stir-fry for 2 to 3 mintues or to desired doneness. Remove beef from the wok. Repeat with remaining beef. Return all beef to the wok.
Stir Nam Prik; add to the center of the wok. Return broccoli to the wok. Stir all ingredients together to coat with Nam Prik. Bring to boiling. Cover and cook 1 mintue more or until heated through. Serve immediately with hot cooked rice. Garnish with chili pepper, if desired. Makes 4 servings.