Puree the tomatoes, onion and garlic in a blender until smooth.
Heat the olive oil in a large skillet over high heat until almost smoking.
Add the tomato puree, cloves, peppercorns, bay leaves and fry, stirring, until thick, 5 to 6 minutes.
Add the stock, reduce the heat and simmer until thickened but still brothy, 25 to 30 minutes.
Season with salt.
Strain, discarding the solids, and keep warm.