Heat a frying pan over medium-low heat. Add the olive oil and butter.
Once the butter has melted add the onions and garlic. Gently fry for at least 15 minutes, stirring regularly, until the onions are very soft.
Stir in the flour, mixing thoroughly.
Gradually add the stock, stirring constantly.
Pour in the wine, continuing to stir.
Add the herbs and simmer for 15-20 minutes, stirring now and again.
Season with salt and pepper to taste.