For starters, Matzoh ball soup has to have a great broth.
Then whether or not your matzoh balls should be light or sinkers, depends upon what you grew up with. In my case, if they're not feathery-light, they're a failure.
Here's my recipe, straight from Grandma Jacobs:
Grandma Jacobs Matzo Balls
Makes about 30
3 large eggs, well beaten
1 cup matzo meal
½ cup warm water
¼ cup chicken fat) vegetable oil doesn’t give the right flavor
1 teaspoon sea salt
Stir up the mixture and chill well (overnight or 3 or 4 hours, minimum).
Fill a large stockpot ¾ full of water and put in a whole onion which has been poked through with a knife. Add 1½ tablespoons salt. COVER THE POT and bring it to a rolling boil.
Form the matzo balls a little larger than golf balls (they will puff up) and slide them into the covered pot of boiling water, one at a time. VERY IMPORTANT TO KEEP THE LID ON THE POT AT ALL TIMES, even between additions of dumplings. When all the matzo balls have been added to the pot, set the timer for 40 minutes. DO NOT OPEN THE POT DURING THE COOKING PROCESS, OR THE KNAIDLACH WILL BE HARD!
At the end of 40 minutes, remove pot from heat and carefully lift the dumplings from the hot water one at a time (using a slotted spoon). Heat them in the chicken soup, and serve.
Wine is the food that completes the meal.