Heat your oven to 200°C/Fan 180°C/Gas 6. Peel the garlic clove. Spoon 2 tbsp out of the rice for later. Tip the rest into a bowl and cover with cold water. Whisk for 1-2 mins till the water goes cloudy. Drain and rinse. Tip into a small pan. Add 400 ml boiling water and the garlic. Cover. Bring to the boil. Turn the heat right down. Simmer over a low heat for 25 mins till all the water is absorbed.
While the rice cooks, thickly slice the fennel, trimming off any dry ends. Place on a baking tray and drizzle with 1 tbsp oil. Season and turn to coat in the oil. Slide into the oven when the rice has 15 mins left to cook.
Zest and juice half the lemon. Roughly chop the rocket. Set aside for later.
Take the rice off the heat and set aside, lid on, to steam while you smoke the cod. This will finish cooking the rice.
While the rice is steaming, place a double layered piece of foil, shiny side down, in the base of a wok. Tip the reserved 2 tbsp of rice into the centre. Scatter over 2 tsp fennel seeds, the sprigs of thyme and a few peppercorns if using. Place the pan on a medium heat and cover with a lid.
When the pan starts to smoke, carefully place the cod fillets in, skin-side down, and season. Cover. Smoke for 5-7 mins till the cod is cooked through with a smoked flavour (it will flake when pierced with a fork). Remove the cod and place on a plate. Leave to cool slightly. Discard the smoking ingredients.
The garlic clove should have broken down with the rice during cooking. If not, press it with the back of a fork and stir through. Add the rocket, lemon zest and juice. Taste and season the rice.
Place mounds of rice on two warmed plates. Top with the smoked cod and roasted fennel. Serve with wedges of the remaining lemon for squeezing.