Set your grill to medium-high heat (around 400 degrees F) and allow it to preheat. Soak the cedar plank if it hasn’t been pre-soaked.
Use paper towels to pat dry the salmon. Drizzle with about 1 tablespoon olive oil and use a brush to coat the top. Season with salt and pepper.
Place the salmon on its pre-soaked cedar plank directly on the grill. Close the lid and cook for about 20 minutes, or until the salmon reaches an internal temperature of 145 degrees F.
Cut lemon in half and place cut-side down onto the grill. After about 8 to 10 minutes, remove the charred lemons and set aside.
While the salmon cooks, place a cast iron skillet on the grill grates. Add about 2 tablespoons olive oil and the diced onion. Cook for 3 to 4 minutes, until softened. Season with salt and pepper.
Add the cut asparagus and snap peas. Sauté for about 7 to 8 minutes, stirring occasionally, until just tender but still bright green. Carefully remove pan from the grill and keep the lid closed until salmon is finished cooking.
Once salmon is cooked, remove it from the grill and begin to assemble.
Spoon the cooked farro into a serving dish. Use a fish spatula to remove the cooked salmon from the plank, which will help loosen the skin, and place the fish onto the farro. Spoon on the warm asparagus-pea salad and squeeze charred lemon juice throughout the dish. Drizzle with extra olive oil.
Toss together fresh herbs and sprinkle onto the dish. Season with extra salt and pepper, as desired. Serve.