In a large pot, bring 5 quarts of water to boiling over high heat.
In a bowl, measure the flour and place the butter on top. Pour hot water over the butter to melt it. Using chopsticks, distribute the liquid evenly in the flour. The mixture will look like large crumbs. Using your hands, knead them into a smooth dough. Cover with plastic wrap and let rest for 15 minutes.
Wash, dry, and chop the herbs or green vegetables of your choice. Use your favorite tools to chop them. Sometime, I feel tlike using my knife, and there are times when I prefer my food processor. Transfer them into a bowl, add crumbled Feta, and use your hands to combine them well. The warmth of your hands will soften the cheese and it'll bind the greens. Use the measuring scoop to divide the mixture into 20 portions, 1 tsp each.
You can make handmade dumplings or using a ravioli maker. For ravioli maker, divide the dough into 4 equal portions. Roll them the same size as the maker. Dust the maker with some flour and make dumplings.
Cook the dumplings in boiling water until they float plus 1 minute, for about 3 minutes total.
Serve warm topped with your favorite savory sauces, sour cream, pesto, etc.