Will robust ethnic foods be a lasting trend or a fad that will soon go the way of crockpots, blackening spices and Y2K rations? The economy might have a say in it: Diners take more risks when their wallets are fat. Hey, what's 15 bucks if you don't like the dish? But when money is tight, customers want to order something familiar. Diablo's menu, happily, is so affordable that it's no big deal when one of those detrimental flavor conflicts lands on your plate. And if you're foolhardy enough to take a crack at it, the Hot Beef Injection is on the house.