Place the bulgur and ½ teaspoon salt in a large heatproof bowl. Add 2 cups boiling water, cover, and let stand until tender, 12 to 15 minutes; drain.
Meanwhile, in a food processor, combine the spinach and mint and process until finely chopped, scraping down the sides of the bowl as necessary.
In a large bowl, whisk together the lemon juice, oil, garlic, and ¼ teaspoon each salt and pepper. Add the bulgur, spinach mixture, tomatoes, and cucumber and toss to combine.
