Cook pasta in boiling water for about 8 minutes, or according to package instructions, until al dente. Add green beans during the last 3-4 minutes of cooking time.
Drain pasta and beans, reserving 3 tablespoons cooking liquid, then return pasta, beans and reserved liquid to pan. Add lemon zest, lemon juice, thyme leaves, garlic salt and 2 tablespoons olive oil.
While pasta cooks, rinse any ice glaze from frozen salmon under cold water; pat dry with paper towel. Heat heavy nonstick skillet over medium-high heat. Brush both sides of salmon with 1 tablespoon olive oil.
Place in heated skillet and cook, uncovered, about 3-4 minutes, until browned. Shake pan occasionally to keep from sticking. Turn salmon over; cover pan tightly and reduce heat to medium.
Cook an additional 6-8 minutes for frozen salmon or 3-4 minutes for fresh/thawed fish. Cook just until fish is opaque throughout.
Break into large chunks (removing skin, if any); add to pasta. Cook and stir gently over medium heat for 1-2 minutes.
Season to taste with salt and pepper. Garnish with lemon wedges and thyme sprigs.