Depends on the size and what you’re serving with it. I’ve always been a bit iffy about slicing and frying a black pudding. Horseshoe black puddings on Lancashire outdoor markets were probably my first encounter with fast food, over sixty years ago. They were boiled, sliced horizontally and served in a large, floury muffin with a dab of psychedelic green mint sauce on top. By contrast, industrial vertically sliced, and fried black pudding always remind me of second rate breakfasts in slightly dingy, provincial hotels.
Whilst the award winning black puddings of Bury, Oldham and Rawtenstall markets and their ilk were exceedingly fine, our local Aveyronnaise and Lotoise boudin noir are a different order of beast if only on account of their size. Slicing and frying seems too crude and immediate, whilst boiling something so large, doesn’t seem sufficiently precise (not hot enough throughout and too much flavour lost). That’s why I prefer steaming - lengthy, but worth it.,
I don’t like the dried crust of a fried black pudding/boudin noir, whereas steamed then slit and disembowelled so the contents spill out is for me the essence of boudin noir - but never mind Normandy apples, instead serve it with Dijon mustard and generously buttered spring cabbage - what more could man possibly want?