Preheat oven to 375°.
Remove white papery skin from garlic head (do not peel or separate the cloves). Wrap head in foil. Bake at 375° for 45 minutes; cool for 10 minutes. Separate cloves; squeeze to extract garlic pulp. Discard skins.
Bring 1 cup water to a boil in a saucepan. Add tomatoes; cover and remove from heat. Let stand 10 minutes. Drain tomatoes in a colander over a bowl, reserving 1/4 cup liquid.
Place garlic pulp, tomatoes, 1/4 cup reserved liquid, oil, and remaining ingredients in a food processor; process until smooth.