POSITION racks in top and bottom-thirds of oven, then preheat to 400F. Line 2 baking sheets with foil. Cook quinoa following package directions.
GRATE one apple half and thinly slice other half and toss with 1 tsp lemon juice in a small bowl.
DIVIDE sweet potatoes, sprouts, 1 tbsp oil and 1/4 tsp salt between prepared sheets, tossing to coat.
STIR pork, grated apple, 2 tsp honey, garlic and 1/2 tsp salt in a large bowl. Form into 12 meatballs. Divide between sheets. Bake, switching sheets halfway, until meatballs are cooked through, 15 to 20 min.
WHISK remaining 1 tbsp oil, 3 tsp lemon juice, 1 tsp honey, 1/4 tsp salt, tahini, zest and 3 tbsp water in a small bowl. Divide everything among bowls, then drizzle with dressing. Top with apple slices.