First prep the broccoli. Cut off the florets into small pieces. Using a vegetable peeler, peel the broccoli stalk to remove the tough outer skin. Slice the broccoli stalk into pieces similar in size to the florets.
Heat the oil in a large skillet and add the onion, garlic, carrots and red bell pepper. Season with salt and pepper and saute for 5 minutes. Add the broccoli florets and stalks and saute for another 5 minutes, then add a few tablespoons of water and cover, cook for an additional 3-4 minutes until broccoli is bright green and tender but still crisp.
Whisk together the peanut butter, soy sauce, rice vinegar, honey and red pepper flakes. Toss the warm stir fry with peanut sauce. Serve over rice garnished with chopped peanuts, cilantro and scallions.