Matzo balls are considered by many to be an integral part of the passover holiday. Depending on your preferences and family history (how your mother & grandmother made their matzo balls) you may like 'floaters' (light fluffy balls) or 'sinkers' (dense, heavy balls).
My preference has always been floaters & over the years I've tried many, many methods to produce them. Some of the techniques have included adding club soda to the dough or, the most sure fire, using shallow soup plates.
All of the techniques seem to rely on one common ingredient, make sure that there is air incorporated into the matzo ball dough. This makes sense and explains how the club soda works. Personally, I think that club soda or seltzer adds too much salt to the dough so I don't use that. That said here's how I make my 'floaters'.
I just use a standard Passover style matzo ball mix (regular matzo ball mix may have leaven in it so you can't use it for Passover). I prepare the mix according to package directions but there here's where I vary.
1) I ALWAYS make the dough the day before & let it rest in the refrigerator overnight, this allows for the maximum hydration of the matzo meal & make the dough very cold which is important for the next step
2) I use a cookie scoop, medium size to scoop out dough balls & once scooped handle them the minimum amount possible. This keeps the dough cold & prevents squeezing out any air bubbles present in the dough. Don't make the balls any bigger than a small walnut, if they are much bigger the outer part of the dumpling with get soggy before the inner part is completely cooked.
3) Cook the matzo balls in boiling hot soup or extra broth. Keep the soup boiling & don't add so many dough balls that it will cool off. This, IMHO is the most important step, the high heat of the soup serves to heat the air bubbles trapped in the dough expand and makes the matzo balls fluffy.
4) Get the dumplings out of the soup when cooked and put aside in a covered bowl until ready to reheat for dinner. If you leave them soaking in the soup, like a sponge they will get sodden with soup an sink.