Boil the shanks. Pour water into a saucepan, place the shanks there, and put on the fire. Bring to a boil, reduce heat to medium, and cook for 1.5 hours. Add lentils to the broth. Cook for 20 minutes. Then add potatoes and salt. Continue cooking for 10 minutes.
Prepare the vegetables. In a frying pan with oil, fry the carrots and onions for 5-7 minutes until golden brown.
Finish cooking the soup. Add the fried vegetables to the pot with the knuckle and potatoes. Add a little more salt. Add pepper. Bring to a boil. Then remove from heat. Let the soup sit for 30 minutes before serving. Then remove the knuckles from the broth, separate the meat from the bones, cut it into pieces, place it back in the pot, and stir.