Make the sauce: mix together the gochujang, soy sauce, minced garlic and sugar and set aside.
Over at the stovetop, heat your Dutch oven, pot or braiser over medium high heat. Add the vegetable oil and the gochugaru and mix together for a few minutes until all the gochugaru is coated with the oil. Add in the chicken, skin side down. After a few minutes, add the onions, the gochujang sauce, and the water. All of the chicken should be just covered with the water. If you need to add more water, add more now. Turn the heat to high to bring everything to a boil. Lower the heat to medium and let everything cook for about 15 minutes.
After 15 minutes or so, add in the potatoes, carrots, and the jalapeños and mix together so everything is covered and coated with the sauce. Cover with lid and let cook for another 12 to 15 minutes, or until the potatoes are fork tender.
Check the potatoes, give everything another good mix and spoon some broth from the bottom of the pot and pour it over the top of the chicken and everything. Garnish with green onions and serve over hot rice. Enjoy!