Finely grate the lemon zest and set aside for later in the recipe. Peel and thinly slice 1 red onion and slide into a bowl. Sprinkle the onion with a pinch of salt and squeeze over half of the lemon juice, and stir well with a spoon to combine. Set aside to quickly pickle while you make the rest of the recipe.
Preheat your oven to 160°C/Fan 140°C/Gas 3. Peel and finely slice the remaining onion. Peel and grate the garlic cloves. Roughly chop the tomatoes into small pieces. Pour 1 tbsp oil into a pan and bring to a medium heat. Scatter in the sliced onion along with half of the garlic, 1 tsp cumin and a little salt and pepper. Cook for 5 mins, stirring occasionally, till softened.
Drain the jackfruit and add to the pan. Spoon in half of the chopped tomatoes and stir well to combine. Continue to cook for a further 10 mins. During the cooking process, stir and mash the jackfruit chunks from time to time with a wooden spoon till the pieces separate into strands. Once cooked, scatter in the lemon zest.
While the jackfruit is cooking, make the black bean salad. Drain the beans and rinse well with cold water. Shake dry and tip into a large bowl. Slide in the remaining tomatoes and garlic. Halve the chilli, flicking out any seeds and membrane for less heat, and finely chop. Stir the chilli into the beans along with the remaining lemon juice and 1 tbsp oil and a pinch of salt and pepper.
Pop the tortillas onto a baking tray and sprinkle with 1 tsp cold water. Slide into the oven to warm through for 5 mins.
Serve the warm tortillas piled with pulled jackfruit, tangy bean salad, quick pickled onions and rocket leaves.