Cut tomatoes into big pieces. Cut off a thin slice from the bottom of the garlic bulb. Keep it in a bowl, drizzle some olive oil and sprinkle salt over it, place the bowl in a hot oven and roast till well browned.
Heat 2 tbsps olive oil in a non stick pan, add onion, tomatoes, bay leaf and salt and mix. Peel some of the garlic cloves and add to the pan, add the remaining bulb as it is. Add thyme and 1 cup water and let it cook.
Add tomato puree and mix. Add basil leaves, crushed peppercorns and mix. Cover and cook for 10 minutes or till the tomatoes become soft. Strain and reserve the stock. Remove thyme and the garlic bulb from the solids. Cool it and grind it to a puree with a little water. Add bread slice and grind it again.
Pour the strained stock and the puree into the pan. Adjust salt and bring it to a boil. Pour the soup into soup bowls and serve piping hot garnished with basil leaves or basil oil.