1. In a small non-stick skillet cook onion and garlic in oil over moderately low heat, stirring, until softened.
2. Transfer mixture to a bowl and stir in mint, salt, allspice, and cinnamon.
3. Add lamb, bread crumbs, egg, and currants and combine well.
4. Form level tablespoons of lamb mixture into 1 1/4-inch meatballs, arranging on a tray as formed.
5. In a small bowl roll half of meatballs, 1 at a time, in black sesame seeds until coated, transferring to a rack set in a shallow baking pan.
6. Coat remaining meatballs with white sesame seeds in same manner, transferring to rack.
7. Meatballs may be prepared up to this point 1 day ahead and chilled, covered loosely.
8. Preheat oven to 450�F.
9. Bake meatballs in upper third of oven 8 to 10 minutes, or until golden and just cooked through.

To Make Yogurt Dip:

1. In a fine sieve set over a bowl drain yogurt, covered and chilled, 3 hours.
2. Discard whey in bowl and transfer yogurt cheese to bowl.
3. Yogurt cheese may be made 2 days ahead and chilled, covered.
4. Into yogurt cheese stir mint and salt.

Makes: 1 & 1/2 cups