Peel the potato and cut into 2cm chunks. Put in a medium saucepan of cold salted water and bring to the boil. Reduce the heat to medium and cook for 6-8 mins until almost tender (the potato won't be fully cooked). Reserve 125ml (½ cup) cooking water, then drain.
Step 2 — Prep ingredients
Meanwhile, preheat the oven to 220C, fan-forced. Finely chop the coriander leaves, discarding the stems. Crush or finely chop 1 garlic clove. Coarsely grate the cheese. Drain and rinse the beans. Lightly grease a 1.25L (5 cup) baking dish (see Kitchen hack).
Step 3 — Brown beef mince
Heat 2 tsp olive oil in a large deep frypan over medium-high heat. Add the garlic and beef mince and cook, breaking up the lumps with a spoon, for 3-4 mins until browned. Add the potato, Tex-Mex seasoning and tomato paste and cook, stirring, for 1 min or until fragrant.
Step 4 — Add vegetables
Add the beans, tomatoes, reserved cooking water and 2 tsp barbecue sauce to the beef mixture and bring to the boil. Reduce the heat to medium and cook, covered, for 5 mins or until slightly thickened. Remove the pan from the heat. Taste, then season with salt and pepper. Stir in half the coriander, then transfer the mixture to the baking dish.
Step 5 — Bake and serve up
Thickly slice the bread, then put the slices on top of the potato mixture. Scatter over the cheese. Bake for 10 mins or until golden. Scatter the remaining coriander on top, then divide among bowls and enjoy!
Step 6 — Kitchen hack
If you have an ovenproof frypan, use it to cook the bake on the stovetop, then simply top with the bread and cheese and put it in the oven, instead of transferring the mixture to a baking dish.