Before Lucien Robert showed up in town, the phrase “Boston food” conjured up images of broiled scrod — and prompted about as much excitement as, say, British food. That began to change in the early 1970s when the French immigrant and his wife, Ann, opened up Maison Robert in Boston’s Old City Hall. The restaurant soon became famous for serving meticulous French cuisine in a spiffy setting, but it also expanded the entire city’s horizons. Maison Robert helped enliven a downtown that had been in decline, deployed locally grown produce and locally caught fish, and provided a training ground for a generation of aspiring chefs. In the decade since the restaurant closed, Boston’s culinary scene has expanded in a host of different directions. There are white-tablecloth restaurants upholding classic notions about fine dining, and there are seemingly casual eateries where the chefs obsess over every morsel on the plate. Robert cleared the way for both. He died Feb. 20 at 87, but his influence remains strong in kitchens all around Boston every night of the week.