Over low heat, sauté the onion in olive oil until it is translucent. Add the tomatoes, bell pepper, garlic, thyme and bay leaf.
Deglaze the pan with the white wine. Add the stock and bring it to a boil. Season with salt and pepper.
Add the artichokes to the pan and cook them for approximately 20 minutes or until tender. Remove the artichokes and reduce sauce over high heat until most of the liquid has evaporated, about 20 minutes.
Place the artichokes in a bowl and pour sauce over them. Correct seasoning to taste. Refrigerate overnight.
When ready to serve, finish artichokes by shaving the truffle on top.