Trim corned silverside/brisket or any excess fat or visible sinew.
Place corned silverside/brisket into a large pot that has a lid with all of the ingredients. Cover with cold water.
Bring the pot to a boil and then reduce to a gentle simmer. Put the lid on pot the and simmer for 2 ½ hours.
Skim any brown scum/foam from the pot as it forms.
Leave corned beef to cool in the cooking liquid.
Warm sliced garlic and olive oil in a small saucepan over low heat for a minute or two. It is important not to fry the garlic, you want it to soften slightly. Place to the side to cool.
In a small bowl soak panko crumbs in milk.
Place walnuts in a saucepan of cold water. Bring to the boil over high heat and then drain immediately in a colander. Rinse walnuts with cold tap water and place back in the saucepan again. Cover with cold water and bring to the boil again. Repeat this process twice.
In a small food processor or blender, blend walnuts, soaked panko crumbs, parmesan, and a pinch of salt until smooth.
Add garlic, oil, and a tablespoon or two of water. Blend until you have a thick sauce. Adjust water as needed.
Season to taste and serve with corned beef.
Store excess sauce in a container in the fridge for up to a week
Juniper Berries: You could try using 1 tablespoon of gin in their place. Alternatively use 6-8 cloves.Fresh Thyme: Freeze the ½ bunch of thyme you don’t use if needed. Simply place in a small plastic bag, as it is, whole on the branches. When you want to fresh thyme, just crush it gently in frozen state with your hand. Hold onto the branches in the bag and shake. The leaves will fall off easily and you tip them into your dish.Carrot: I don’t bother peeling the carrot, simple wash it and cut in into quarters. Cut it down the middle to form two long halves and then cut across the middle of each long piece to form two shorter ones.Onion:Trim roots from the base of the onion. Cut the onion in half from top through the base where the roots were. Then peel the skin from the onion (it is easier to peel when it is cut in half). By keeping the base where the roots were attached it will keep the onion halves from falling apart.