DtG, the way I prepare it is I clean it up by peeling or scraping then chop it into small pieces and pop them into a food processor. I get that buzzing and add vinegar to get it into a thick slurry. You can add salt (~ 1 tsp/2C horseradish). I then pack that into clean pint canning jars with a couple of tsp of sugar on top (this keeps it from oxidizing and turning brown). It will keep in the refridgerator 'til next year. If you don't have a food processor you can grate it - that's how my mother used to do it - but a gas mask is handy when preparing it that way.
As for my venison pot roast - I brown a small roast on all sides, remove from pot and add chopped onions and garlic, sautee 'til softened, deglaze pot or skillet with some red wine and/or some stock, add herbs (I used some thyme, bay leaf and black pepper). Throw in some chopped celery and carrot and simmer for a couple of hours. Remove roast and blend veggies in sauce and add a couple of tablespoons of horseradish to that. Serve with mashed potatoes or I also like to have it with kasha (buckwheat groats).