Soak your cedar plank for 1-2 hours before use. (You can soak it in plain water or kick things up a notch by soaking it in wine or cider!) Once the plank is ready, remove it from the liquid, dry it off, and set it aside.
Preheat your oven to 450° F and your grill to medium heat, about 350° F.
Remove your salmon from the fridge and pat your fillets dry with a paper towel. Let the salmon sit out and come to room temperature; this ensures an even cook. This should take about 15 minutes. (Don't put the salmon on the cedar plank yet; you need to place the plank on the grill solo first. Keep the salmon on a portable surface, like a plate.)
In the meantime, in a small bowl, mix together the minced garlic, basil, thyme, rosemary, olive oil, salt, and pepper. Evenly spoon this mixture over the salmon fillets and, with clean hands, gently press the rub into the fillets; set aside.
Place the fennel, tomatoes, olives, and broccoli rabe into a large bowl. Drizzle with olive oil and season with salt and pepper. Toss the salad with your (clean!) bare hands, gently massaging the oil into the broccoli rabe leaves. (The florets don't need to be massaged.) You can add a bit more oil if needed. Once the salad is well tossed, spread it out over a baking sheet and roast for about 15 minutes, or until the tomatoes burst and the fennel is tender. Stir halfway through cooking time.
Once you put the salad in the oven, place the cedar plank on the grill by itself and let the plank sizzle and crackle for about 30 seconds. Then, carefully transfer the salmon fillets from plate to plank. Place a lemon slice on each fillet. Cover, and let the fillets cook for about 12-15 minutes, checking for doneness at the 12 minute mark. You want your fillets to have an internal temp of 140° - 145° F. (The fillets will continue to cook after being removed from the heat; an ideal internal temperature at serving time is 145° F.)
With grilling gloves or hefty oven mitts, carefully remove the plank from the grill.
Plate your fennel and broccoli rabe salad, place fillets on top, sprinkle with fennel fronds, and serve; squeeze fresh lemon juice over your plate before digging in for an extra punch of bright and fresh flavors.