Instructions
Click on your Sim to bring up his cell phone menu. Call Abraham Finkel or the Sim that asked you to cook a group meal and invite him over. Click on Abraham when he arrives at the door to invite him inside.
Click on the stove or refrigerator and select the "Serve Breakfast/Lunch/Dinner" option, depending on the time of day. Choose whichever meal you would like to make and your Sim will automatically begin cooking.
Click on the finished meal when your Sim places it on the counter and drag it over to your inventory.
Click on Abraham Finkel to deliver the group meal. If you do not have the option to deliver the meal to Abraham when you click on him, it means you need additional portions of the meal. Repeat the cooking process until he is satisfied.