Bring potatoes and salt to boil in water, approx 20 mins. When cooked, drain and add milk, 2 tsp butter and mash well. Keep hot.
Make gravy according to recipe on pack. Keep warm.
In a large nonstick frying pan on medium heat, add one Tbsp of oil and onions. Reduce heat slightly and cook onions until caramelized. Remove and mix into gravy.
In the same pan on medium heat add the extra tsp of oil, then cook the English Pork sausages. While browning sausages approximately 20 mins, cook the peas according to packet recipe, drain then add mint and butter to coat. Keep hot.
To serve spoon potato mash on each plate. Place sausage neatly on top and smother with onion gravy. Serve with a side of minted peas.