Mix the batter. In a medium bowl, beat the eggs with the salt. Whisk in the matzoh meal and chicken stock. Mix in the chicken fat, then stir in the dill. Cover and refrigerate for at least 2 hours.
Boil water. Bring a large, wide pot of water to a boil. Add 1 Tbsp kosher salt.
Form the balls. Using a 2 Tablespoon scoop, portion the mixture. Wet your hands and gently roll each portion into a round ball.
Cook. Add matzoh balls to the water. Reduce heat to a simmer, cover, and cook for 90 minutes.
Check doneness. Cut one in half—it should be the same colour all the way through. If not, simmer a few minutes longer.
Drain and store. Drain matzoh balls. Make up to 3 days ahead; store in a single layer on a baking sheet, cover, and refrigerate.