Combine cheese, jalapenos, herbs, onion, limejuice and salt in a small bowl and mix well. Fold in crabmeat and set aside. Spread margarine on one side of each tortilla.
Place one by one in a non-stick pan coated with cooking spray, margarine-side down. Spread ½ cup crab mixture over half of tortilla and cook over medium heat for 3 mins or until underside is golden brown. Fold over the other half and transfer to serving plate and keep warm.