Make the pickled daikon: In a small bowl, toss the daikon with the salt. Transfer to a colander and let drain for 45 minutes. Rinse the daikon well with cool water and transfer to a glass jar. In a small pot, bring the rice vinegar, sugar, water and turmeric to a boil. Pour over the daikon to cover and let cool completely. Can be made up to 1 week in advance.
Make the roasted vegetables: Preheat the oven to 450° and line a baking sheet with foil. In a large bowl, whisk together the honey, soy sauce, vegetable oil, Korean red pepper flakes and gochujang. Add the daikon, carrots, radishes, garlic and lemongrass, and toss to coat. Season with salt.
Spread the vegetables onto the prepared baking sheet in an even layer. Roast, turning occasionally, until tender and caramelized, 30 minutes.
Transfer the vegetables to a platter and top with ½ cup pickled daikon and sliced scallions. Serve immediately with the remaining pickled daikon on the side.