1. Peel and finely slice the onion.
Peel and cut the carrot into rounds.
Trim and cut the leeks into rounds.
Peel and dice the turnip and potatoes.
In a saucepan, heat the oil.
Sauté the onion and leeks for 3 to 5 minutes (they should be tender).
Add the carrot rounds, turnip dice, and potato dice.
Cook for 2 minutes, stirring.
Dissolve the 2 bouillon cubes in boiling water.
Pour this hot broth over the vegetables.
Bring to a boil, then reduce the heat and simmer covered for about 20 minutes (the vegetables should be tender).
In a bowl, dissolve the cornstarch in 4 tablespoons of milk.
Pour the remaining cold milk into the saucepan with the vegetables.
Add the corn and the dissolved cornstarch.
Mix well.
Heat gently until the soup thickens.
Season with salt and pepper.
Serve in bowls, sprinkle with freshly chopped parsley, and enjoy.