Back in January, we raved about Branch Line, the Garrett Harker empire’s Watertown outpost: its soaring ceilings, the great beer-and-wine roster, the amazing rotisserie chicken, the amiable hospitality, the free parking. But the dish we can’t help ordering whenever we return is the sugar snap pea salad, a complex, verdant stunner of crisp, finely sliced sugar snaps, red onion, mint, fresh ricotta and a piquant Marcona almond vinaigrette. We never thought a salad could haunt our dreams.