Butterfly the turkey; use a pair of strong pountry shears to remove the spine - reserve for gravy. • 1 fresh turkey
Cut around the wishbone using a paring knife and remove it from the bird, and use the pountry shears to place a deep cut in the center of the breastbone from the back, so it’s easier to crack.  
Flip the bird over, and press down between the breasts to flatten the turkey. Place on a large rimmed baking sheet. Combine the salt and baking powder in a medium bowl, whisking until well-incorporated. Liberally dust the bird with salt until it looks like it’s been covered in a light snowfall. • 2 cups kosher salt
• 1 Tbsp baking powder
Refrigerate, uncovered, overnight.  
Preheat oven to 400° F.  
Brush the salt off the turkey entirely and place on a wire rack.  
Line a rimmed backing sheet with the chopped vegetables and place the turkey and rack on top. • 6 cups chopped carrots, celery, and onions
Roast for 90-120 minutes, depending on the size of the turkey - breast should register 155° F, while thighs 175° F.  
Allow the turkey to rest for 30 minutes.