Home made onion rings are always a treat.
Place all the dry ingredients in a bowl large enough to hold the finished batter.
Whisk in the egg to form a stiff batter. Make sure there are no dry patches.
Add the seltzer water is small portions, ensuring each addition is well mixed before adding the next.
Allow the batter to rest, in the cooler, for 10 minutes. Adjust the consistency if necessary.
Batter and fry your onion rings.
Try using other veggies such as broccoli or zucchini strips or cauliflower. The recipe does make a bit of batter which won't last till the next day. It will also work well for some fish for fish and chips.