Soak the onion in cold water. This prevents tears when you peel them. Finely chop the carrot, celery, celery leaves, parsley and onion.
Heat the olive oil in a frying pan and add the carrot, celery, celery leaves and parsley and sauté. Add the onion and keep sautéing.
Add the sugar, black pepper (preferably cracked with a mortar and pestle) and whole wheat flour. Mix well and simmer over low heat for about 30 minutes. Season with salt, taste and add a little more if needed.
Sterilize a jar, and pack the sauce in the jar. Store in the refrigerator after cooling, where it will keep for 3 weeks.
I used a pressure cooker without the lid (no pressure used). The bottom of the pot is thick so food doesn't burn easily. I used 2 tablespoons of sugar.
Serve with grilled fish and zucchini.
Serve with cheese on toast, or use as a sandwich spread.
Serve with roast beef.
Use in salads.
Story Behind this Recipe
I bought some sauce onions intending to simmer them in balsamic vinegar, but I didn't have enough vinegar, so I adapted a recipe for Italian onion sauce I saw in a booklet.
Add salt sparingly at the end while tasting the sauce. Cook over low heat so as not to burn the sauce. I recommend using a thick-bottomed pan.