Preheat your Instapot or electric pressure cooker to the “Saute” setting.
Slice the Top of the Rib in long, wide strips against the grain, cut into 3 to 4 inch cubes, and generously season with Kosher salt and ground black pepper. In small batches and without crowding the bottom of the pot, sear all of the Top of the Rib and place aside.
With the “Saute” setting still on, cook the onions, carrots, and celery with white pepper, cumin, chili powder, and paprika until fragrant, about 4 to 5 minutes. Add a little beef stock and gently stir the vegetables, lifting any little brown bits from the bottom of the pot. Once fragrant, mix in the remaining beef stock, puree pumpkin, pinto beans, and pureed tomato. Add the seared Top of the Rib to the chili mixture.
Secure the lid into the “Lock” position and turn off the “Saute” function. Turn on the “Pressure Cook” function and set for 70 to 80 minutes. During the first 10 to 15 minutes, pressure will build up in the device and then it will begin to countdown while it cooks. Allow the device to cook the entire time. Once finished, release the pressure in a safe way according to your device's instructions.
Once pressure is fully released, remove the lid. Using tongs or two forks, gently shred the Top of the Rib.
Serve your Kosher Top of the Rib Pumpkin Chili with your favorite toppings such as chopped chives, cilantro, and avocado!