Hey, what better way to observe NBC-Universal's Green Initiative than to customize a big ole 18-wheeler semi-truck "equipped with power and water, and includes a state-of-the-art kitchen with the capacity to accommodate 38 guests per seating" and drive it around America when gas has vaulted over $4/gallon? That's the thinking behind "Top Chef: The Tour," which is coming to L.A. on Friday. Former contestants (or, per the press release, "chef'testants" - clever or no?) from the reality-competition show will do a series of little cooking demonstrations for you and yours. The private seatings are all already booked, but on Friday from 3:00-4:00p.m. at CityWalk, Richard Blais (from season four) and Brian Malarkey (season three) will do a public appearance. Maybe you'll get a little appetizer for free or something! (They won't be cooking from this stove, we're pretty sure.) Then it's off to Des Moines. According to their itinerary, it'll take a week for the 18-wheeler to galumph across half the country. ...