Pan-Seared Sirloin Steak with Creamy Root Vegetable Mash
A restaurant-quality British steakhouse dinner that delivers tender, juicy sirloin with a golden crust paired against silky mashed potatoes and celeriac enriched with butter and milk. Earthy kale adds a slight bitterness and nutritional punch to the mash, creating a sophisticated side that enhances simple comfort food. The contrast of textures—crusty exterior on the steak, fluffy mash beneath—makes this special. This dish suits home cooks seeking impressive weeknight dinners or weekend entertaining without fuss. Serve it as a special occasion main or elegant date night at home. What sets this version apart is the combination of celeriac with potato, which adds subtle nuttiness and prevents the mash from becoming too stodgy, while finishing the kale at the last minute preserves its color and structure rather than turning it gray.
Ingredients
- 2 sirloin steaks
- 9 oz sirloin steak
- 1 lb Maris Piper potatoes, peeled and cut into 1 ⅛" chunksrusset potatoes1:1potatoes
similar starch and texture, floury when cooked
- 11 oz celeriac, peeled and cut into 1 ⅛" chunksparsnips1:1root-vegetables
same cooking time and creamy texture
- 1 ¾ oz kale, roughly chopped
- whole milk, a glug(optional)
- butter, a small knob(optional)
- olive oil, for frying
- salt, to season
- black pepper, to season
- buttered peas, to serve(optional)
- mustard, to serve(optional)
Instructions
- 1
Remove the steaks from the fridge and allow to come to room temperature.
- 2
Bring a large pan of water to a boil and cook the potatoes for 15-20 minutes.
- 3
Add the celeriac after 5 minutes of cooking.
- 4
Add the chopped kale for the final 2 minutes of cooking.
- 5
Drain the vegetables well and return to the pan.
- 6
Mash with milk and butter until smooth, season with salt and pepper.
- 7
Cover and keep warm over low heat.
- 8
Heat a large frying pan over high heat until smoking hot.
- 9
Oil the steaks on both sides and season with salt and pepper.
- 10
Fry for 2.5-3 minutes on each side.
- 11
Rest the steaks in a warm place for 5 minutes.
- 12
Serve the steaks alongside the vegetable mash with buttered peas and mustard if desired.
Tips
Bring steaks to room temperature before cooking for even, predictable results and more tender meat. Cold steaks cook unevenly and contract sharply, squeezing out juices.
Rest steaks for 5 minutes minimum after cooking. This allows carryover cooking and lets muscle fibers relax, redistributing juices throughout rather than losing them on the plate.
Add kale in the final 2 minutes only to preserve bright green color and prevent it from turning drab. Extended boiling leaches color and increases bitterness.
Good to Know
Leftover mash keeps 3-4 days refrigerated in an airtight container. Reheat gently with a splash of milk. Cooked steak keeps 3-4 days and is best served cold in salads or at room temperature.
Prepare and cut vegetables up to 8 hours ahead. Mash can be made 2 hours ahead and reheated gently. Do not cook steaks ahead; sear fresh to order.
Serve hot on warmed plates. Classic sides include buttered peas, mustard (English mustard or wholegrain), and crusty bread to soak up juices. A simple green salad offers brightness.
Common Mistakes
Skip bringing steaks to room temperature to avoid uneven cooking and dense, tough meat.
Don't drain vegetables thoroughly to avoid watery, split mash.
Cook kale beyond 2 minutes to avoid losing its color and developing strong sulfur notes.
Don't rest the steak to avoid juices running onto the plate instead of staying in the meat.
Substitutions
Dairy-Free Swaps
General Alternatives
same cooking time and creamy texture
FAQ
Can I make the mash ahead of time?
Yes. Make it up to 2 hours ahead and keep covered at room temperature or refrigerate. Reheat gently in a pan over low heat with a splash of milk to restore creaminess. Do not microwave, as it separates the mash.
What if I don't have celeriac?
Substitute parsnips one-to-one. They cook in the same time and create similar creamy, sweet mash. Turnip or swede work too but use half the amount as they have stronger flavor. Avoid all-potato mash as it becomes gluey when overworked.
How long can I keep cooked steak?
Cooked steak keeps 3-4 days in the coldest part of your fridge. Serve chilled in salads or gently warmed. Freezing steaks after cooking dries them out. Fresh raw steaks freeze well for up to 3 months.