Soak the split peas for a few hours or overnight. Drain and rinse them before cooking.

Finely grate one carrot, half of the parsley root, and half of the celeriac. Dice the remaining carrots into large cubes and dice the remaining parsley root and celeriac into small cubes.

Heat cooking oil in a large pot over medium heat. Once hot, add the grated carrot, parsley root, and celeriac. Sauté for 5–7 minutes, stirring frequently, until softened and lightly golden.

Add the diced carrots, parsley root, and celeriac to the pot. Sauté for 2–3 minutes, stirring frequently.

Add the drained split peas and sauté for 1 minute, stirring constantly to prevent sticking.

Pour in water, stir well, and cover the pot with a lid. Once the water comes to a boil, add the bay leaf, dried thyme, salt, and pepper.

Lower the heat and simmer the soup for about 1 hour, stirring occasionally, until the split peas are tender. If the soup becomes too thick while simmering, add more water as needed to reach desired consistency. Remove the bay leaf, taste it, and add more salt and pepper if necessary. Serve hot.