The sauce, for two:
The arrowroot can be replaced by cornflour if you don't mind a slightly cloudy sauce.
Slowly mix the water with the arrowroot. You don't want lumpy sauce.
Add the port, sugar, butter and cranberry jelly, and stir over a medium / low heat. After a few minutes, the butter will have melted, and soon afterwards the sauce will begin to thicken. Continue to heat and stir for another few minutes.
The sauce can be made up to an hour in advance if it is kept warm.
The meat:
Venison fillet steaks tend to be relatively small and thin, so either go for two per person or pile on the side plates (new potatoes and salad is a good choice in summer). Do not let the price tag deceive you — there's not much meat on a Bambi.
Frying the steaks is a last minute job. Use a very high heat and an oil with a high smoke point — grapeseed oil is a good choice. Cook for two to three minutes on each side (thicker steaks may require slightly longer). The meat is best when it is still slightly pink in the middle, similar to a medium / rare beef steak.
Pour on the sauce, and serve immediately.