first of all you make the matzo mixture because it has to be chilled in the refrigerator for as long as possible. i basically used the recipe on the manischewitz box container except i substituted olive oil for vegetable oil. traditionally they're supposed to be made with schmaltz. also i used seltzer water because the jews say that it makes the matzo balls lighter.
mix together all of the ingredients in a bowl, adding the seltzer last and more lightly with your hands until uniform. don't worry that it looks to too runny because it will firm up in the fridge. Cover and refrigerate while you make the soup.
put chicken thigh in a pot and add water until the chicken is submerged plus about 2 inches. bring to a boil then, simmer for 30 minutes.
meanwhile, quarter the onion, chop one carrot and one stalk of celery into inch wide pieces, and crush the garlic. dice the other stalk of celery and carrot into 1/2 inch pieces and set aside for later.
skim the top of the stock with a wire mesh spoon. add the onion, garlic and big vegetable pieces along with 1 tbsp salt. cover and simmer for an hour.
bring a pot of water and a little salt to a boil then reduce to a simmer. fill a shallow bowl with cold water. take the out the matzo meal and form into balls with a tablespoon and your hands. make sure to dip your hands and the spoon in the water between every ball. drop each of the balls into the water then cover and let simmer for about 20 minutes. the matzo balls should expand about to 1 1/2 their original side; i made six from the mixture.
remove the chicken from the pot and strain the soup, discarding the vegetables. return the broth to the pot and add the remaining carrots and celery. Bring to a boil then simmer for 10 minutes or until the vegetables are almost tender.
meanwhile remove the skin from the chicken and tear the meat into shreds. add the chicken shreds back into the soup and simmer for another 5 minutes. remove from heat and taste. Add the pepper and more salt if necessary.
test the matzo balls with a fork. you should be able to insert it without feeling any change in pressure within. transfer the balls to the soup pot with either a slotted spoon or tongs. cover and let sit for 15 minutes so that they can absorb the flavor. reheat if necessary and serve.