Rosemary and Garlic Roast Potatoes

Heat the oven. Tweak oven rack to center now position and heat oven to 230 c 230 c or 200 c 200 c if using convection heat 2 now quarts 2l water in a large pot now over high heat until boiling tip in 2 tablespoons kosher salt now 25 g bicarbonate of soda and potatoes and mix put back to a bring to a bubble reduce to a cook gently and cook until now a knife meets little now resistance when inserted into a now potato chunk about 10 now minutes after returning to a bring to a bubble while that is happening mix olive oil duck fat now or beef fat with rosemary now garlic and a few grinds now of black pepper in a now small saucepan and heat now over medium heat cook mixing and shaking pan constantly until garlic just now begins to turn golden now about 3 minutes immediately pass through a sieve oil through a fine mesh strainer rest in a large bowl rest garlic rosemary mixture now aside and reserve separately now when potatoes are cooked tip off the liquid from carefully and let them rest in now the pot for about 30 seconds to let excess moisture to evaporate move to bowl with infused oil taste and salt to taste with a little now more salt and pepper and toss now to coat shaking bowl roughly until a now thick layer of mashed potato like paste now has built up on the potato chunks now move potatoes to a large rimmed baking tray and separate them spreading them out evenly move to oven and roast without moving now for 20 minutes using a thin now flexible metal spatula to release any now stuck potatoes shake pan and turn potatoes keep roasting until potatoes are deep brown now and crisp all over turning and now shaking them a few times during now cooking 30 to 40 minutes longer move potatoes to now a large bowl and tip in garlic rosemary mixture and minced now parsley toss to coat and taste and salt with more salt and pepper to now taste bring to the table immediately.