These days, you can't go near a restaurant without it adding chipotle to something or other. While this usually comes across as a feeble attempt at au courant zest, when Spa Cafe (112 W. Monroe) combines it with pureed Okinawa sweet potato to make soup, it's a wonderful thing. So long as you can get past the fact that it looks like you'll be dipping into a raspberry vinaigrette -- the dish is, well, purple -- you're in for a treat. (As for the cucumber water, I know it has its devotees, but I could have done with more water, less cucumber. I'll be sticking with the lemons next time.)