Submerge planks in water for at least 1 hour before use
Set grill to medium high heat (400 degrees)
Melt butter. Add salt, dill, and lemon to butter and brush lightly over salmon fillets. Place cut lemon rings on top of fillets
Skewer vegetables alternating between onion, zucchini, and tomato. Drizzle with olive oil and season to taste with seasoning salt and pepper
Place skewers of vegetable on the grill, rotate every few minutes
Remove from grill when zucchini has begun to slightly soften and onion and tomatoes have a slight charred look
Place cedar planks on the grill and shut the lid. When they begin to smoke (1-2 minutes) place salmon, skin side down, on the planks over direct heat and close lid. NOTE: You must close the lid otherwise the planks will flame up.
Remove planks with salmon after 5 minutes for medium rare temperature. Continue cooking for 1-2 more minutes for medium to well done temperature