Heat the oil in a large saucepan over a moderate heat and cook and stir the rice and onion for 2 minutes. Pour in the fish stock or water together with the bay leaf and thyme. Reduce the heat to low, cover and simmer until the rice is tender, about 20 minutes. Discard the bay leaf and thyme.
Fold the salmon gently into the rice with the tomatoes, parsley, spring onions, dill or tarragon, and chives. Fold in the avocado, and season with salt and pepper to taste.
Instead of smoked salmon, you could use a tin of boneless red salmon, or a pre-cooked salmon fillet.