Preheat the oven to 200*C. Halve, peel and chop the onion into small pieces. Peel and grate the garlic (or use a garlic press). Zest and quarter the lime. Drain and rinse the black beans in a colander. Pop the beans in a medium bowl and roughly crush with the back of a fork or potato masher.

Heat a drizzle of oil in a large frying pan. Once hot, add the onion and cook until browned, 4-5 mins. Add the veggie mince and cook until piping hot for a further, 4-5 mins. Add the tomato puree, BBQ sauce and water (see ingredients for amount) and half of the chipotle paste, cook stirring, for 1 minute. Add the garlic and cook for a further minute.

Meanwhile, heat a medium sauce pan on medium heat. Add the black beans with the remaining chipotle paste and a splash of water. Stir and cook until the mixture is piping hot, 1-2 mins. Season to taste with salt and pepper and keep to one side.

As the beans and chilli bubble away, slice lengthways into the avocado. Once you reach the stone, turn the avocado around to cut it in half. Twist each half and pull it apart. Remove the stone then scoop out the flesh onto a board. Chop into small pieces then pop into a bowl. Season with salt and pepper and lightly crush the avocado. Set aside for later.

Lay the tortillas on a large baking tray in a single layer and drizzle with a little oil. Season with salt and bake on the top shelf of the oven until golden and crispy, 4-5 mins. Once done, top each with equal portions of black bean mix, then the veggie chilli and lastly the avocado.

Share the tostadas between your plates. Sprinkle on the lime zest and serve with wedges of lime. Enjoy!