We have done the Sunrise Safari while my aunt has also done the culinary tour you're remembering. I called her for details as I didn't attend and she stated that upon checking in at Boma around 4pm the tour group spent the next "30 or so" minutes touring both Boma and Jiko. They were given samples (bread and a zebra dome is what she remembers) while tour guides took them through the dining rooms and explained the African influences, etc. "It was free" was how she ended the conversation!

And FWIW, she also gave the tour two thumbs up.