If time allows, soak chickpeas in water to cover overnight; if not, boil in water to cover for 2 minutes, then soak for 2 hours.
In a pot, combine chickpeas and tomatoes in water to cover and simmer, partially covered, until chickpeas are very tender, adding water if necessary. Drain, reserving a little cooking liquid.
Combine in a food processor with salt, pepper, garlic, oil, pimenton, if using and reserved cooking liquid as necessary to get machine going. Puree, then add lemon juice to taste, along with more oil, pimenton or salt, if desired. Serve with pita chips or raw vegetables. (This will keep, refrigerated, for about a week.)