Preheat the oven to 200C/400F.
Cook the bacon using your preferred method to your desired texture. Chop just before needed.
Halve the potatoes and toss them on a very large greaseproof baking tray with 2 tbsp oil, 1/2 tsp salt and a good pinch of black pepper. Flip them all over so they're cut side down (use 2 trays if you need to).
Roast them for 15-20 minutes, or until they turn golden, a little crispy and are soft enough to smash. Use a potato masher or other suitable utensil to press down on the potato and smash them to even thickness (the thinner they are the crispier they'll be; just make sure they don't break apart). Drizzle with a little more oil if they're looking dry. I also like to season with a pinch more salt.
Place them back in the oven for another 20-30 minutes until the potatoes are deep golden and crispy. Timings will be dependent on how big the potatoes are, so just be vigilant and use your best judgment. If you notice the ones around the outside charring a little too quickly, just remove them if needed. The potatoes will crisp a little more as they cool.
Meanwhile, in a large mixing bowl combine all of the remaining ingredients (bar the bacon). Once everything is evenly distributed, toss through the potatoes and bacon, then serve up with extra parsley if desired. Enjoy!