If you are using dried morels, remove them from the soaking water and pour the liquid into a small saucepan. Reduce over high heat until you are left with about ¼ cup of liquid. Turn off the heat, pour into a small bowl and set aside.
Pour the stock into the same saucepan and reduce it to ½ cup over high heat. If you are using dried morels, add this reduced stock to the mushroom liquid. If you are using fresh morels, heat a skillet over high heat for 2 minutes. Turn the heat down to medium-high and place the morels in the pan to heat. They will release their water quickly. Let this boil until the water is almost all gone, then add 3 tablespoons of the butter and the shallot. Cook for 3 to 4 minutes, stirring often. Remove and set aside. If you are using dried morels, you do not need to dry-cook them first. Cook them with the shallot in the butter.
Heat a clean pan over high heat for a minute or 2 and add the grapeseed oil. Heat this for 1 minute. Pat the venison dry with a paper towel and place it in the pan. Sear it for 3 to 4 minutes on one side, then flip. Let it cook through to your taste on the other side without flipping again, another 1 to 3 minutes. Remove from the pan and set aside under foil to rest.
Add the remaining 1 tablespoon butter to the pan and let it melt over medium heat. Add the flour and stir to combine to make a roux. Cook, stirring constantly, for 2 minutes. Add the wine and stir to combine. It will thicken immediately, and if it turns to a paste, add the reserved stock. If it does not turn to a paste, let the port boil a minute, then add the stock. Add the morels.
Once the morels are heated through, lay down a pool of the sauce on 4 plates, then top with venison. Arrange the morels around the meat. Grind black pepper over all and serve at once.