Heat your oven to 200°C/Fan 180°C/Gas 5. Pour 1 tbsp fennel seeds into a pestle and mortar, and crush. No pestle and mortar? Pop the seeds into a sturdy bowl and crush with the bottom of a jam jar. Slide the seeds into a bowl. Sprinkle in a pinch of dried chilli flakes.
Peel and crush or finely grate 1 garlic clove. Grate the zest off the lemon. Strip and finely chop the rosemary leaves. Add the garlic, lemon zest and rosemary to the fennel and chilli bowl. Stir in 1 tbsp olive oil and a pinch of salt and pepper.
Pop the pork belly strips into a large roasting tin. Rub all over with the fennel and rosemary mixture. Slide into the oven and roast for 10 mins.
Meanwhile, scrub the potatoes and cut into small bite-size chunks. After 10 mins, add the potatoes to the same roasting tin as the pork. Toss the potatoes with 1 tbsp oil and a pinch of salt and pepper. Slide back into the oven for 20 mins.
While the pork and potatoes are roasting, make the parsley salsa. Peel and grate the remaining garlic clove onto a chopping board. Peel the shallot and finely chop it. Combine the shallot and garlic on the board. Top with the parsley, and chop together as finely as possible. Slide the mixture into a bowl.
Squeeze the juice from the lemon into the bowl and add 1 tsp of the Dijon mustard. Stir in 1 tbsp oil and a little salt and pepper. Have a taste, and add more seasoning or mustard if needed. Set aside.
After the potatoes have roasted for 20 mins, remove the tin from the oven. Turn the pork and potatoes over. Return to the oven for 15 mins, till everything is golden and crispy.
Trim any woody ends from the rainbow chard, and roughly shred the leaves and stalks. When the pork and potatoes are nearly ready, warm a frying pan to a medium-high temperature. Slide the chard into the pan along with 3 tbsp cold water and a pinch of salt and pepper. Stir fry for 3–4 mins, till tender.
Transfer the roasted pork belly and potatoes to plates, and pile the greens on the side. Spoon over a little of the parsley salsa and serve.