Purple Cauliflower Mashed Potatoes

Mashed potatoes have always been one of my favorite comfort foods, but what if I told you could make a simple addition that adds an extra layer of flavor while making them a visual treat as well? Many members of the brassica genus contain a high concentration of amino acids, which gives them a strong taste of umami. The Irish take full advantage of this in classic Colcannon by pairing cabbage with mashed potatoes, and I created these Blue Mashed Potatoes using purple cabbage, which tints the finished dish a striking bluish-purple.

Cauliflower, another brassica, brings a similarly savory profile, but I like how its creamy, tender texture blends in better with the mashed potatoes. While white cauliflower works perfectly, I couldn't resist adding a layer of visual drama by using purple cauliflower to make it a little extra.

What's fascinating about purple cauliflower is its color-changing magic. Its vibrant hue comes from anthocyanins, natural pigments that react to changes in pH. In an acidic environment (lower pH), the color shifts red, while an alkaline one (higher pH) shifts it toward blue. Since tap water tends to be slightly alkaline, it can dull the vibrant purple color, so I like to add a splash of vinegar to the boiling water to preserve that vivid hue. 

You can also tweak the color of the mash by adding some lemon juice. The acidity brightens the lavender tone and adds a subtle zing that beautifully balances the richness of the cream and butter. Too much lemon juice can shift the color to magenta, though honestly, potatoes are just as pretty in pink!

Finally, I like leaving the cauliflower chunky for some added texture and rustic charm. If you prefer a silky-smooth mash, puree the cauliflower into the potatoes with a hand blender. Just be sure not to over-blend, or the potatoes will turn gummy.