Soak your cedar planks in water for at least 1 hour.
Preheat your grill to 400°F (medium-high heat).
Combine the smoked paprika, garlic powder, onion powder, black pepper, and salt in a bowl and mix until well incorporated. Season each piece of salmon lightly on all sides.
Remove the cedar planks from the water bath and place your salmon portions on top, skin side down. Be sure to space them at least 2 inches apart for even cooking.
Add a slice of lemon to the top of each salmon portion (optional).
Place your cedar planks directly on the grates of your grill and shut the lid.
Let them cook for 15 to 20 minutes, or until the internal temperature reaches 135°F or to your preferred doneness (see Notes).
Remove your salmon from the grill and serve immediately.
Notes
Cooking time can vary depending on the grill you are using and how thick or thin your salmon portions are but generally the salmon will take 15 to 20 minutes to reach medium-rare (125°F to 130°F). If you like your salmon a little more on the done side, use the guide below: