Heat a large frying pan over medium. Add 1 tbsp vegetable oil, then 3 minced garlic cloves. Cook garlic until fragrant, about 2 min. In a small bowl, whisk juice from 1 lemon with 1 tsp cumin and 1/4 tsp salt. Add to pan. Heat for 1 min. Drain and rinse 2 540-mL cans lentils, then stir in until well coated. Remove from heat. Stir in 1/2 cup chopped fresh mint. Season with pepper.