For the tzatziki, coarsely grate the cucumber by hand using a box grater or process in a food processor using the grater attachment.Wrap the grated cucumber in a tea towel and squeeze over a sink to remove as much excess liquid as possible, then add it to a large bowl together with the remaining ingredients. Mix everything well and refrigerate until needed.
Warm the olive oil in a heavy-based frying pan over medium–low heat, add the onion and garlic and saute for 3–4 minutes, or until they are softened and fragrant. Stir in the cinnamon, cumin, oregano and tomato paste and cook for a further 2–3 minutes. Add the Tender Jack, coconut aminos or tamari, sweetener and vinegar. Mix everything really well and, using the back of your spoon, squash the jackfruit pieces slightly. Add the pepper and ground chilli, if you like, bring to a gentle simmer and cook for another 10–15 minutes, or until the sauce is lovely and sticky. Remove from the heat.
Preheat the oven to 200°C and line a baking tray with baking paper.
Spread the jackfruit mixture onto the prepared tray, transfer to the oven and cook for 20–25 minutes, or until the jackfruit pieces are slightly caramelised and beginning to brown around the edges.
To make the flatbreads, combine the almond meal, arrowroot or tapioca flour, garlic powder, coconut milk, water and salt in a bowl and mix well to form a smooth, thinnish batter. (The more watery the batter, the thinner and crispier your flatbreads will be, so add a splash or two more if you like.)
Melt 1 tablespoon of the coconut oil in a small non-stick frying pan over medium heat. Add 125 ml (1⁄2 cup) of batter to the pan, tilting and swirling
it to coat the base in an even layer, and cook for 2–3 minutes, then carefully turn the flatbread over with a spatula and cook for a further 2 minutes, or until golden and cooked through. Lift the flatbread from the pan and set aside wrapped in a clean tea towel to keep warm. Repeat with the remaining mixture, greasing the pan with a little coconut oil in between flatbreads to make sure they don’t stick to the pan.
To serve, arrange your flatbreads or lettuce leaf ‘cups’ on a platter and top with the tomato quarters, shredded lettuce and sliced cucumber and onion. Spoon over the baked jackfruit, dollop on the tzatziki and enjoy with some lemon wedges for squeezing.