If this is your first time making doughnuts, cook one doughnut first as a test. If you are cooking the doughnuts on the stove top, you may need to adjust the temperature down slightly as the doughnuts cook. Be very careful when deep frying: make sure children and pets are away from the stove or deep fryer, and ensure all tools and utensils are dry to prevent splattering.
LIne a cookie sheet with parchment paper for placing the uncooked doughnuts. Place a wire rack over another cookie sheet for the cooked doughnuts, If you have paper towels or napkins available, you can line the wire rack with these to absorb grease from the doughnuts.
In small bowl, beat buttermilk, vegetable oil, eggs and vanilla until thoroughly mixed.
In large mixing bowl stir together flour, sugar, nutmeg, baking powder, baking soda and salt. Add buttermilk mixture and stir until no streaks of flour remain. (If the dough is very soft, sprinkle rolling surface with an additional 1/2 cup / 125 ml flour and knead gently into dough. Use additional flour as needed for rolling. )
Roll or pat dough into 1/2-inch / 2.5 cm thickness and cut out with doughnut cutter. If you do not have a doughnut cutter, you can use two different sized cutters. Use the larger cutter first, then cut out the center with the smaller cutter. You can re-roll the centers, or fry them.
Place doughnuts on a parchment-lined sheet while you heat the oil. S
Stir together the 2/3 cup / 160 ml sugar and 1 teaspoon / 5 ml nutmeg in a bowl. Set aside. You will use this to roll the slightly cool doughnuts in.
Heat oil in deep fryer to 375 degrees F / 190 degrees C or to the temperature specified for doughnuts on your appliance. Follow the directions for your fryer to determine how much oil you need to add. If you are using a saucepan, you will need at least 2 inches / 5 cm of oil in your pot, and ensure that there is at least 2 inches / 5 cm of space between the top of the oil and the edge of the pot . Using a thermometer, heat the oil to 360 - 365 degrees.
When oil is heated, add 2-4 doughnuts to your oil depending on the size of your fryer or pot. Doughnuts must have space between them to cook properly. Do not overcrowd your oil. Cook for 2-3 minutes and doughnuts appear darker on the edges. Turn over and cook for an additional 2 minutes. The doughnut middles will cook more quickly than the bigger doughnuts.
Remove doughnuts from the oil with tongs, and place on prepared wire rack. Cook remaining doughnuts.
Roll slightly cooled doughnuts in the nutmeg sugar before serving.
Do not use olive oil for deep frying. Safflower oil, canola oil, and corn oil are all suitable for deep frying.
The amount of oil you need will depend on the method you are using and the size of your fryer. You will need several cups at least. Deep fryers tend to use more oil than the stove top method.