Heat the oven to 180C.
Score the fat in the pork loin, and remove skin if necessary. Season with salt.
Blend the onion, fennel seeds, garlic, paprika, lemon zest & juice, veg oil and balsamic to a thick marinade.
Set the pork in a dish and rub the marinade on and into the scored fat.
Cover and leave for at least 20 mins.
Roast uncovered for 1 hour.
Remove and rest for 5-10 mins.
Lightly dress the rocket and tomatoes with olive oil, salt and pepper.
Toast the pittas.
Cut open and spread with hummous.
Fill with slices of pork, tomatoes and some rocket.