Soak whole head of lettuce in cold water to make it crisper. Thinly slice the peppers and julienne the carrots. Saute peppers for a few minutes, then add carrots and saute some more. Add chickpeas to warm them, then add okonomi sauce, soy sauce and rice vinegar. Add sugar if needed to balance. Reduce until sauce is thick. Cut lettuce into pieces, then mix in the vegetable mixture. Garnish with a lot of sesame seeds.