In the Snack Bar after Edward Burra   Is it the loud lights that pull you in or the glimpse of a woman with scarlet lips, her elbows nonchalant on the long white counter, or the bodies   of cured meats hanging in a row above glistening trays of beetroot, chopped tomato and pickled cucumber? Jazz rhythms begin in your head:   syncopations on the piano, hurtlings from a huge silver mouth—this is life as you’ve never known it. But even as you step inside you can see   there’s too much knife and fork and the slices he’s cutting…