Marinade & tofu
To make the marinade, mix the peanut butter with all the other ingredients up to and including the garlic. Add the tofu to the marinade, cover and chill for at least 1 hr.
Remove the tofu, wipe away the marinade and set aside. Fry the tofu on all sides in a non-stick frying pan, remove from the pan, set aside.
To fill the tacos
Pour half of the reserved marinade into the pan, heat through. Add the cucumber, jalapeños, coriander, lime juice and reserved tofu, fill the taco shells with the mixture. Serve with the remainder of the marinade.