Simmer uncovered to reduce excess liquid
Mix cornstarch with cold water and stir in gradually
Mix flour with cold water or broth and stir in gradually
Add a roux made from butter and flour
Mash a few cooked potatoes into the broth
Stir in instant potato flakes a little at a time
Add a slurry of arrowroot and cold water
Add more dumpling dough if the broth is too thin
Let the dumplings cook longer to release starch
Stir in a small amount of heavy cream
Add a beurre manié made from softened butter and flour
Use less broth next time for a thicker result