On the stove top, heat olive oil and butter in a large Dutch oven. Add the onions and cook until softened, but not browned.
Add the garlic, bacon and mushrooms and cook for another minute.
In a frying pan, brown the diced venison a handful at a time and add to the stew. When all the meat is browned, add the beef stock, redcurrant jelly and salt and pepper.
Bring to a boil and stir well. Put the lid on the stew and place in the middle of the oven – cook for 90 minutes.
Remove from the oven. Make a paste with the corn starch and two tablespoons of water. Add as much of the paste to the stew as is needed to thicken the sauce – add a little at a time if you are not sure how much you will need.
Transfer the stew to the stove top, and, on a low heat, cook until the gravy has thickened – this will take about five minutes.