Heat the olive oil over medium-high heat in a medium saucepan. Add the onion and garlic and cook, stirring occasionally, until soft but not browned, about 4 minutes. Add the beans, ham hock, and cilantro. Pour in enough water to cover the ingredients by 2 inches. Toss in the bay leaves and bring the water to a boil, then adjust the heat so it is boiling gently. Cook the beans until tender, about 2 hours. Keep an eye on the beans; they should always be covered by liquid. When the liquid meets the level of the beans, top it off with cold water. Toward the end of cooking, ease up on the liquid you add; the goal is to have the beans barely covered with liquid by the time they're tender.

Drain the beans, reserving the liquid. Discard the turkey wing or ham hock and the bay leaves. (Leave the cilantro in with the beans.) Put the bean mixture in a food processor and process, gradually adding enough of the reserved liquid, until the beans are the consistency of mashed potatoes. Season, to taste, with salt and pepper. Mound the beans on a platter and garnish with tortilla chips and radish slices, if using. (The beans can be prepared up to 30 minutes in advance. Return the beans to the saucepan and keep warm over very low heat.)