Remove the steak from the refrigerator 30 minutes before cooking to bring up to room temperature.
Heat the grill for 10-15 minutes before cooking the steaks.
Lightly brush oil over the grill grates.
Season the porterhouse steak with kosher salt and cracked black peppercorns.
Place the steak on the grill and cook for 3-4 minutes. Turn steak 90 degrees to acquire the grill cross-marks and cook for an additional 3-4 minutes. Flip steak over and repeat on the second side. After cooking on the second side, move the steak to an indirect heat side of the grill to finish cooking for an additional 7-12 minutes. This will depend on the thickness and cooking temperature desired.
While the steak is cooking, toss the zucchini in the canola oil, salt and pepper. Place on the direct heat of the grill and grill for 2 minutes and then turn 90 degrees to get grill marks and cook 2 more minutes. Flip zucchini and repeat for the next two sides to get grill marks and cook through. Remove from heat and set aside to serve.
Cook the steak to your desired temperature. Color is not an accurate indicator of final cook temperature. Ensure final cook temperature reaches 145 F for 3 minutes. Let steak rest for 5 minutes before slicing.
Cut steak off the bone and slice into thin pieces. Place back next to bone and serve alongside the zucchini.