In a large pot, stir together the grapes, sugar, and lemon juice. Bring to a boil over medium heat, and cook for 20 minutes or until grapes start to burst open.
Add vinegar, salt, and pepper. Return to a boil. Reduce heat to low, and cook for 30 minutes, or until thick.
Place in jars and cover with lids. Leave on counter until cooled, then place in frid