Preheat oven to 325. Place first 3 ingredients on paper towels, squeeze until barely moist. Weigh or lightly spoon flour into dry measuring cups; level with a knife. Combine flour, cumin, 1/4 teaspoon salt, eggs, and onions in a bowl; beat with a mixer at low speed until combined. Heat a large non-stick skillet over medium heat. Add 2 teaspoons oil; swirl. Heap 3 tablespoons of potato mixture into pan to form a patty; flatten slightly. Repeat procedure 5 times to form 6 patties. Reduce heat to medium-low; cook 6 minutes on each side or until golden brown. Place latkes on a baking sheet; keep warm in oven. Repeat procedure twice with remaining oil and potato mixture to yield 18 latkes total. Sprinkle latkes with 1/4 teaspoon salt. Garnish with dill, if desired. Combine apple and remaining ingredients in a food processor; process until smooth. Serve with latkes.