1. Preheat oven to 325 degrees Fahrenheit.
2. In a small bowl, combine cumin seeds, fennel seeds, ground cumin, ground fennel, and a generous pinch of salt and pepper. Rub spice mixture over the meat side of the lamb breast. Place lamb in a large roasting pan and cover tightly with foil. Cook for three hours.
3. Remove lamb from pan and let cool slightly. Slice in between the bones to create small ribs. Pull apart the rest of the meat, incorporating some of the fat as you go.
4. Spoon tahini onto a large platter, creating a well. Place pulled meat inside the well and sliced ribs on top. Add roasted tomatoes and garnish with fresh mint and toasted pine nuts.