These butter-roasted onions are perfect yet simple. Try them with good quality sausages and mash for a twist on the classic fried onions. When roasted, onions, which can be quite pungent when raw, turn sweet and delicious.
Onions to use for Butter-Roasted Onions
For this Butter-Roasted Onions recipe, try and source the largest white onions available. Most supermarkets sell large onions loose or in packs of three. However, most supermarkets also sell smaller onions in larger batches. These would be best avoided. This is because the onions will cook too quickly before they have time to caramelise, resulting in softer onions that have lost their bite.
White onions can be bitter and pungent when eaten raw, making red onions the preferred one when making a salad. However, roasting onions produces a sweet and mellow flavour completely different from the raw vegetable.
To prepare the onions, peel the onions and remove the tops and bottoms. However, the root part of the onion helps keep the onion together, so try to remove the furry outside bit while allowing the root to remain intact, thus keeping the onion together. Then, cut in half.
Rosemary & Sage – Sage has a strong flavour and aroma, so use it sparingly. It works well with pork, which may explain its use here since I designed it to work with my honey & mustard-glazed sausages. Rosemary, too, has a strong flavour, even if it’s quite fragrant. These herbs are used sparingly here as too much would drown out the taste of the onions.
Butter – Butter helps give richness to the onions while adding another layer of sweetness. You could make this recipe vegan by substituting butter for olive oil. Still, you’ll lose a layer of flavour sweetness and find getting a nice, caramelised exterior a little more challenging.
Reduced Balsamic – Reduced balsamic is a syrupy-like balsamic vinegar condiment. It’s balsamic vinegar brought to the boil with sugar and reduced to a thicker syrup-like consistency. It’s sweet and tangy, making it perfect to compliment the sweet onions and counteract their natural sweetness simultaneously.
Salt & pepper, to taste. Obviously.
- 3 White Onions Peeled, Tops and Bottoms Trimmed, Cut in Half.
- 1 tsp Sage Chopped
- 2 tsp Rosemary Chopped
- 30 g Butter softened.
- 20 ml of Reduced Balsamic Vinegar to serve
- Sea Salt Flakes
- Cracked Pepper
- Preheat the oven to 190C or 170C Fan or 375F or Gas 5
- Trim the tops and bottoms of the onions.
- Transfer the onions to an oven-proof dish. Mix the butter with the sage and rosemary, then top each onion with an equal-sized knob. Add a splash of water to the bottom of the dish to help the onions steam as they cook, approximately 50ml.
- Cover with foil and roast for 45 minutes.
- Remove the foil, turn the temperature to 220C, and roast for 15 minutes until the tops are golden brown.
- Drizzle with balsamic, sea salt flakes and black pepper to serve.