Press garlic. If cooking the salmon, cook in a small amount of oil in a pan. If using tinned salmon, drain and remove from tin. Mix together cucumber, tomato, avocado, chives, garlic, and dill in a bowl and set aside.
Whisk together 2 TBS lemon juice, olive oil, salt and pepper in a separate bowl. Toss with cucumber mix when ready to serve. Divide cucumber mixture between 4 plates and serve with salmon.