3 cups flour
2 tsp salt
1 tsp baking powder
1/3 cup canola oil
1-1 1/4 cups warm water
2 Tbsp oil (or rendered chicken fat)
1 small yellow onion, peeled and diced
1 small red potato, peeled and cut into chunks
1/2 lb boiled chicken (or chicken substitute, either gluten or a product made to resemble chicken breast)
1/2 tsp salt
1/4 tsp pepper
up to 1/2 cup stock
Add the dry ingredients to the bowl of a food processor or mixer, and blend until well-mixed. With the blender going, drizzle in the oil, and then the smaller amount of water. Mix until smooth. Check the consistency -- it should be soft and smooth, but not too tacky. Add the remaining water if it's not smooth enough (or more flour if it's too sticky). Place the dough in a covered container so it doesn't dry out, and allow it to relax at room temperature for least 1 hour.
Heat the oil (or chicken fat) in a cast iron or saute pan over a medium heat. Add the onions, and cook until well-caramelized (aka just the good side of burnt). This will take about half an hour. Turn the flame down if they're going too quickly -- a nice slow cooking will yield the best flavor.
While the onions are cooking, toss the potato chunks into a small pot and cover with water. Bring to a boil, and simmer until they're tender.
When the onion and potato are ready, put them in a food processor or meat grinder with the chicken. Process until everything is broken down into a rough puree. If you're so inclined, you can also add some of the skin from the boiled chicken, which gets chopped up and contributes a luscious richness to the finished dumplings. Mash the ground chicken and and potatoes and onions together with your hands or a wooden spoon, seasoning to taste with the salt and pepper. Add stock if needed for moistness -- you want to make sure it's not too moist, or else it will soften the dumpling dough. Add just enough stock to make it like a spreadable pate. If you use faux meat, you might not need any stock at all.
To Assemble and Cook the Kreplach:
Take the dough that's been relaxing, and roll it out on a floured countertop to a thickness of 1/4" to 1/8". With a 2-inch round cutter (or drinking glass), cut out as many circles as you can. Pull up the remaining dough scraps, and re-knead into a ball (it's best to do this step now, so that the dough has a chance to relax before being re-rolled). With a tiny ice cream scoop, or two spoons, place a ball of filling (about a tablespoon) onto each dough circle. Fold the dough around the filling to make a half-circle, pressing the edges to seal. Take the two corners and press them together, creating a tortellini shape. Place shaped dumpling on a well-floured cookie sheet. Roll out remaining dough scraps, and repeat the process.
When the kreplach are all shaped, bring a pot of salted water to a boil. Throw in a dozen or so kreplach. They will sink to the bottom, but then float to the top fairly quickly. Once they've all floated to the top, simmer for an additional minute. Remove with a slotted spoon, toss with a bit of neutral-flavored oil (like canola), and spread on a cookie sheet or plate. Repeat until all kreplach are cooked. At this point they can be either frozen for future use, or floated in a bowl of soup and served.