I've just had this for tea and it was very, very good. It was based on a recipe I'd seen in a Hugh fearley whittingstall book which used salt beef but I had some leftover roast venison so I used that. Even the kids had seconds.
6 boiled potatoes cubed
2 diced onions
4 cooked beetroot cubed) I used a pre cooked pack from supermarket)
diced leftover roast venison
salt, pepper cayenne and smoked paprika
soften the onions in a big frying pan, add the venison, spuds and beetroot, season with the salt etc, stir round a couple of times then flatten the mix with a fish slice to mush it up slightly.
leave it to cook for a while till you get crispy bits on the bottom, then flip over the hash with the fish slice and do the same to the bottom so it's nicely browned and sticking together.
we had it with brown sauce and pickled red cabbage, very simple but very tasty.
Apparently its it's called red flannel because the White of the spuds and the red of the beetroot make it look like a tea towel!