Eating at Neptune can be annoying: There’s usually a wait, the tiny dining room (only 42 seats) is crowded and noisy, and the staff seems constantly harried. Just remind yourself that it wouldn’t be so crowded if it weren’t so good. This is the best seafood place in the North End—some say in all of Boston—and the quality doesn’t flag even on the busiest weekend night. Start with oysters, enticingly displayed in the window on beds of ice. Move on to anything that sounds good; even the burger is terrific, but I prefer to concentrate on the seafood specials. The signature dish is the lobster roll, served either cold with mayonnaise or hot with butter.