Heat your oven to 220°C/Fan 200°C/Gas 7. Scrub the potatoes and slice into chips roughly 1-2cm thick. Scatter the chips in a roasting tin and pour over 1 tbsp oil. Sprinkle over a generous pinch of salt and pepper and toss together well, till coated. Slide into the oven and roast for 25 mins, turning halfway, till crispy and tender.
Meanwhile, slice the cucumber in half lengthways and use a teaspoon to scoop out the seeds. Slice the flesh into 1cm chunks and slide into a sturdy bowl. Peel the shallots and thinly slice them. Pick the mint leaves and finely shred them. Stir both into the cucumber bowl.
Grate the zest off the lime into a separate bowl and set aside. Squeeze half of the lime juice into the cucumber. Sprinkle in a little salt and pepper and add 1 tbsp oil. Use the end of a rolling pin or the bottom of a jam jar to bash the cucumber slightly, then give everything one final stir and set aside.
Peel the garlic cloves and crush or finely chop them. Halve the chilli, scraping out the seeds and membrane for less heat, and thinly slice.
Pour 1 tbsp oil into a large frying pan or wok and bring to a medium-high heat. Add the pork strips and fry for 3-4 mins, stirring occasionally. Stir in the chopped garlic, chilli and 2 tbsp tamari. Cook for a further 1-2 mins, till the pork is cooked through. While the pork cooks, separate the lettuce leaves.
When the pork is ready, scoop some into each lettuce leaf and top with the bashed cucumber. Scatter over lime zest and remaining juice. Serve with the chips on the side.