A Korean barbecue chain and a sushi chain share many of the attractive qualities of those fast-casual leaders.Burrito chain Chipotle Mexican Grill (CMG -0.12%) and Mediterranean concept Cava Group (CAVA 0.23%) are undeniably stock market darlings in the restaurant industry. Over the past year, Chipotle's shares are up 70%, and Cava's are up by a whopping 150%. Investors are simply enthused with what they see.There's good reason for that enthusiasm. Their businesses are both doing remarkably well, and invest ...