Who has the best veggie burger? Back in June, the Los Angeles Times food section featured a reader’s letter describing the one at Upper West as “the best…on the planet.” Though we liked the burger a lot, we were hardly prepared to crown it with the world title (see June 16 review). The Shangri La Veggie-Nut Burger at M Street Kitchen (2000 Main Street, at Bicknell, in Santa Monica), however, seems at least to be a plausible contestant. Made from mushrooms, white beans, and onions, according to our waitress (we also tasted carrots and celery), the patty pulls off the textural coup of a crisp, brown outside paired with a moist, flavorful, non-mushy inside. Served on a toasted, buttery bun reminiscent of Upper West’s brioche, along with shredded lettuce, a slice of tomato, red onion, sweet pickle slices, and a sweet dressing, it made for an utterly scrumptious sandwich. (The accompanying coleslaw, a lightly dressed, slightly bland rendition, at least held on to a nice cabbagey crunch.) We were impressed, as well, by the brussels sprout salad, which elegantly combined the autumnal brassica, steamed, tamed of its bitterness, and broken down into individual leaves, with judicious slivers of mild, buttery Manchego cheese; almonds, for a nutty crunch; chewy dried cranberries and blueberries, for little, sweet bursts of fruit flavor; and a light, subtle honey-mustard vinaigrette. The vegetarian tacos were less remarkable: Though we liked the simplicity and wholesomeness of the white rice and black beans (albeit with a gratuitous spoonful of sour cream on top), as well as the bright, fresh guacamole and pico de gallo and the tangy, dark hot sauce, we were underwhelmed by the grilled veggies—red pepper, hot peppers, squash, and asparagus, which were apparently unseasoned as well as partially charred (for a burned flavor that we never really like). Moreover, the five small corn tortillas were not nearly enough to encompass the contents of the plate, which quickly devolved into a mess. For dessert, we chose the Magic Brownie, a generously sized chocolate square topped with chocolate sauce, with a dollop of whipped cream on the side. Though neither the brownie nor the cream was overpoweringly sweet, we would have preferred at least a hint of bitterness as a counterpoint to the sugar. We ended up cutting the rich, fudgy chewiness of the brownie with glasses of milk, which our waitress was kind enough to provide at our request (just as she had thoughtfully divided our brussels sprout salad into two plates). Though we would be inclined to avoid the tacos in the future, we would gladly return to M Street Kitchen for that memorable salad and the excellent veggie burger, both of which exhibit the extra portion of care that makes this stylish but friendly eatery extend its M to an mmmm.