Turn the broiler on high and place a large cast iron pan in the oven while it is pre-heating.
Pat the salmon dry with a paper towel. Drizzle the olive oil over the salmon and sprinkle with salt and pepper to season. When the oven is hot, place the salmon, skin side down, into the cast iron pan and broil for 10-12 minutes, until the fish is firm and entirely cooked through.
While the salmon is in the oven, place the lettuce, radicchio, cucumber and avocado into a large bowl and toss with enough green goddess dressing to coat.
Remove the salmon from the oven and serve alongside the salad.