Cut the onion, green onion, and carrot into bite-sized pieces.

Make small cuts on the sausages to ensure they cook evenly.

Prepare the demi-glace sauce by heating 1 tbsp cooking oil and 1 tbsp flour in a pan, stirring well.

Add 1 tbsp ketchup, 1 tbsp soy sauce, 1 tbsp sugar, and 1/2 tbsp vinegar to the pan and stir well.

Add 2/3 cup water to the pan and stir until the mixture is smooth.

Simmer the sauce over high heat until thickened. The demi-glace sauce is now ready.

Clean the pan and sauté the sausages over medium-low heat until cooked through.

Add the vegetables starting with the ones that take longer to cook, such as onion and carrot.

Add the green onion and stir-fry until softened.

Pour the prepared demi-glace sauce into the pan and mix well. Add 1 tbsp soy sauce and 1 tbsp ketchup for additional seasoning.