Put onion, fennel, and lemon juice in a medium saucepan and cover with 1 inch of water.
Bring to a boil and simmer for 5 minutes.
Remove from heat and put in the 2 portions of fish, seasoned with sea salt.
Sprinkle with capers and parsley and cover the pan.
Simmer for about 8 to 10 minutes, until fish is almost flaky.
Place the vegetables in the bottom of a shallow bowl and the fish on top; drizzle with olive oil, and sprinkle with fresh parsley.
Serve one cup of steamed brown rice per person on the side, if desired.