Matthew will be very pleased to see  marinating in the fridge when he comes home.  We love them, and now that they are readily available at Joyco Foods (3288 Pierce Street, Richmond), we are able to have them often.  I have also purchased them at Tokyo Fish Market (1220 San Pablo Avenue, Berkeley), one of my main sources of sashimi grade fish and such things.  Joyco is in Pacific East Mall, and they sell lots of good frozen things – but know your prices before you buy.  When I was there the other day there was a guy unloading a large box of fresh hamachi collars, so that’s what I got, paying about $15 for two, huge, full collars, each yielding two servings.  The collar is that part of the fish between the head and body, and you get bones and all.  A whole collar equals 360 degrees around the fish.  I threw them in a bowl with some Soy Vey teriyaki sauce (else just mix soy sauce, chopped garlic, sugar and a dash of pepper to make your own) and allowed them to marinate in the fridge until I was ready to convect-blast them, which you need to do right before service.    You can also just salt and pepper them and serve with lemon wedges — it’s up to you.  When you are ready, spread out on a rack over a sheet pan lined with foil.  Use the foil if you use the teriyaki sauce because this will drip down and the sugar will caramelize into hard candy that you’ll need to blast out with sand.  You have been warned.  Preheat the oven to 375 F. convection (400 F. if you lack convection) and roast for 10 minutes.  Turn down 50 degrees and cook until done, depending upon the size, but don’t overcook.  For my humongous collars I added an additional 15 minutes.