Place broccoli in a steamer basket; place in a small saucepan over 1 in. of water. Bring to a boil; cover and steam for 3-4 minutes or until crisp-tender.
Meanwhile, in a small skillet, saute onion in butter until tender. Reduce heat; add the sour cream, salt, paprika, poppy seeds and cayenne. Cook and stir for 2-3 minutes or until heated through. Transfer broccoli to a serving bowl. Spoon sauce mixture over broccoli; sprinkle with peanuts.