In a medium bowl, combine the ground pork with the bell pepper, garlic, ginger, chile sauce, fish sauce, sesame oil and 1 tablespoon of the grape seed oil.
In a large skillet, heat the remaining 1 teaspoon of grape seed oil until shimmering. Add the pork mixture and stir-fry over high heat, breaking it up, until it is cooked through and starting to brown, about 8 minutes.
Stir in the water chestnuts, scallions, oyster sauce and cilantro and remove from the heat.
Spoon the pork into bowls. Stack the lettuce leaves on plates. To eat, spoon the pork onto the lettuce leaves, roll up and eat.