Weigh 150 grams of the cooking liquid into a measuring jar and pour it into a big frying pan. If you don’t have enough liquid, just add more vegetable broth.
Also add the agar powder and mix it well to dissolve the powder. Then lay the leeks next to each other in the broth. Cover the pan with a lid and start heating it on a medium heat. Move the pan every now and then to prevent the leeks from coloring on the bottom.
You want to simmer everything for at least 3 minutes.
Meanwhile make your cutting board slightly wet with water and cover it tightly with plastic wrap. We make it wet so the wrap sticks better. Now normally I would do this on my worktop, but because it’s natural stone it’s going to remove all the heat from the leeks and I need as much time as possible before the agar starts to set. That’s why I roll this one on my cutting board.
Once you have laid the wrap and the leeks have simmered for at least 3 minutes remove the lid and place the leeks in the middle of your cutting board. Make a nice stack and then roll it into a tight rouleaux. Try to give it as much pressure as possible without pressing all the liquid out of the leeks.
Now make a knot on one side and use the other side to make the roll even tighter. Just be sure that there is no air trapped in the rouleaux. Then tighty up both sides and let the terrine set in ice water. We do this in ice water so it can float and no dent will form on the bottom.
Let it set for at least 2 hours and add more ice when necessary.
Once it has cooled down and it’s all the way set we can portion it into the desired thickness. Do this with a long sharp knife and really try to let the knife do the work. Mine are around a centimeter thick and then you can make 14 slices out of the terrine. Keep them covered in your fridge for later.
