Green lentils cook in about 20 minutes on the stove top. You don't need to pressure cook them. Just remember as with all legumes with a skin, cook them ALONE in water until fully cooked and mushy and then add your ingredients. 

(The skin on legumes tightens when exposed to salt or acidic ingredients and that stops the water from getting inside the legumes and cooking it. This results in the legume not getting cooked inside no matter how long you cook them.)