Set your non-dairy milk out to warm to room temperature. Melt your butter in a small saucepan and then allow to cool to room temperature. Set both aside.
Make your chia eggs by mixing the water and chia together and setting aside for at least 5 minutes
Sift and whisk together the flour, sugar, and salt in a large bowl.
Place the 3tbsp of aquafaba in a bowl and mix with a hand mixer on high speed until it turns white and stiff peaks form (approximately 5-7 minutes). It can take longer depending on the shape of your bowl and how easily to the mixer can beat the aquafaba.
Sprinkle the yeast over 3tbsp of slightly warm water. Let it sit for 5 mins or until the yeast starts to react. Sprinkling a little bit of sugar in the mixture can help the reaction occur.
Add the yeast mixture, chia eggs, additional 3tbsp of water, milk, butter, and vanilla extract to the dry ingredients. Mix until a dough begins to form. When the mixture begins to look dough like, add the aquafaba. If the aquafaba has gotten foamy and no longer holds stiff peaks, beat again until the peaks form and then add to the dough.
Once a soft dough forms, knead by hand in the bowl or on a lightly floured surface for 10-15 minutes. Be generous in using flour on your hands, but the dough should remain slightly tacky.
After kneading, return the dough to the bowl, cover and let rise until doubled in size. This will take approximately 30 minutes; however, the time can vary a lot depending on the temperature of your kitchen and many other factors. Try to find a warm spot in your kitchen or home to place your dough and it can speed up the process.
After rising, divide the dough in half. Recover the second half of the dough.
Roll out the dough with a rolling pin to about 1/4 inch thick and use a circle cookie cutter to make donuts. Set them aside. Reroll dough as needed.
Repeat with other half of the dough.
Use extra dough to make donut holes by rolling into small balls.
Heat the oil in a large pot. The amount of oil will depend on the size of your pot, but you’ll want at least 2.5 inches of oil.
Heat the oil between 320-360 degrees F. It’s important to stay below 360 and above 320 while frying the donuts, so you’ll need to keep rechecking the oil temperature throughout and readjusting the dial.
Place 2-3 donuts in at a time (depending on the size of your pot).
Fry on one side until light golden brown, then flip and repeat. Remove donuts from oil and place on paper towel lined plates. Repeat with all donuts and donut holes.
Transfer donuts to a wire rack to cool. Once completely cooled, you can fill with your choice of fillings using a piping bag.
To fill the donuts, you'll first want to pierce through with a chopstick or skewer to the center or about 3/4 of the way through (be careful not to poke to the other side). The use a piping bag to fill the donuts.
Dust with powdered sugar and serve.