Peel potatoes and cut them into 1-inch cubes so they cook faster. Add potatoes to cold water and season water with salt and pepper.
Cook potatoes until fork-tender and drain off the cooking liquid. Make sure to reserve some cooking water from cooking potatoes, don’t drain it all completely.
Add butter and milk and mash potatoes while it’s still hot. If needed, add a little more water, a little at a time, checking the thickness while mashing potatoes. Taste to see if more seasoning is needed.
Cabbage:
Preheat a large saute pan over medium heat. Thinly slice leek and cabbage and set it aside.
Dice bacon into small pieces and add it to the pan. Add a little bit of canola oil if needed. Saute bacon until browned and fat is rendered.
Add leek and saute until softens. Then, add cabbage and season with some salt and pepper.
Cook over medium-low heat, stirring occasionally, until cabbage is fully cooked and soft. It will take about 10-15 minutes.
To combine potatoes and cabbage, simply add sauteed cabbage and bacon to the pot with mashed potatoes and carefully mix until combined.
Stir in fresh scallions into the mixture.
Video
Notes
Storing: Store colcannon in an airtight container in the refrigerator. Properly stored, it will last 3-5 days. Remember to always use a clean utensil when scooping out leftovers from the storage container and don’t leave utensils in the container while storing.
Freezing: You can freeze cooled prepared potatoes and cabbage in a freezer bag or airtight freezer food storage container. Get all of the air out and freeze for up to 3 months. Thaw overnight in the refrigerator. Mix well once thawed and reheat until warmed through.
Make Ahead: You can make the entire dish according to the recipe and transfer it into a casserole dish. Cover tightly with plastic wrap and keep refrigerated for 1-2 days. When you’re ready to serve it, pull it out of the refrigerator and let it sit on the counter for a few minutes to warm up.
Reheating: You can reheat it in the oven or in a slow cooker. Before reheating, take off the plastic wrap. In the oven, you can cover it loosely with a sheet of aluminum foil and reheat at 350°F for 15-30 minutes (depending on the size of the dish), just until heated through. In a slow cooker, spread the cold Colcannon and cover with the lid. Let it heat up on LOW heat setting for about 30-40 minutes, until heated through.