Preheat the oven to 425F. Toss the sweet potatoes with the vegetable oil, syrup, a generous pinch of coarse salt, and a few turns of pepper. Place the potatoes on a lined baking sheet and roast for 35-40 minutes, or until very tender and gently caramelized, stirring them once halfway through cooking.
While the potatoes roast, bring 3 1/2 cups water to boil. Add the bulgur and lower the heat to a simmer. Simmer for 8 minutes, stirring occasionally. Remove the bulgur from heat, cover, and let sit for 10 minutes. Drain any excess water from the bulgur and fluff the grain with a fork.
Whisk together the olive oil, orange juice, lemon juice, red wine vinegar, garlic (if using), salt, and pepper.
When the potatoes are ready, transfer them, along with the cooked bulgur, parsley, mint, red onion, and orange zest, to a large mixing bowl. Add the dressing. Toss everything well to combine, then taste the salad and adjust seasonings as needed. Serve.