In a large saucepan, combine rounded ¼ cup cornstarch with ¾ cup milk. Stir with fingertips until you can no longer find any lumps. Add 1 cup tahini, 2 cups 2% milk, ¾ cup sugar. Heat mixture on high until milk is steaming, reduce heat to medium to low and cook for 3-5 minutes until mixture thickens. Remove from heat, and pour through fine-mesh wire strainer. Stir in ¼ cup toasted sesame seeds.
Cool custard and freeze in ice-cream freezer.
TIP: Use soy milk instead of cow’s milk and you’ve got vegan ice cream! The fat from the tahini helps make a very rich ice cream. Tahini has more fat per tablespoon than whole cream, so despite using fat-reduced milk, this isn’t low-calorie.