If using dried beans, combine the soaked beans and 6 garlic cloves in a large sauce pan and add cold water to cover by 1 inch. (If usung canned beans, skip to step 2) Bring to a boil, reduce heat and simmer until soft, about1 to 1 1/2 hours, adding boiling water as needed to keep beans covered. Drain.
In a food processor (or blender) combine the beans, garlic and chiles and process until coursely mashed, with the motor still running add the olive oil, process until smooth. Season to taste with salt and pepper to taste. Transfer to a bowl, garnish with fresh cilantro and serve at room temperature.
You can make this a day ahead, but be sure to bring it to room temperatuter and wait to garnish it with cilantro until ready to serve.
Note - To roast the chiles you can either use a grill or under the broiler, under very high heat, either case you want to place them about 4 inches away from the high heat and blacken the skin (since poblano chiles are un-even, you don't have to wait until ALL the skin is totally black, just use your best judgement and do not burn the chile meat), don't burn the chiles, just blacken the skin, turning when necessary then place them in a plastic bag and let them sit for about 10 minutes, after that, the skins should just slide off, discard the skin.
Hint - When I use a broiler instead of the grill to roast the chiles, I add a dash of liquid smoke to the mix, like 1/4 of a teaspoon.
Time does not include cooking of the beans.