Halve them and roast cut side down. Do not boil them — the vitamin C leaches into the water and the sulphur smell worsens.
2 servings30 min
Heat the oven to 200°C.
Pull off the wilted outer leaves, trim a thin slice from the base, and halve each sprout lengthways.
Dry them completely. Wet sprouts steam instead of roasting.
Toss with the olive oil, salt and pepper.
Lay them out in a single layer, cut side down. Crowded, they will not colour.
Roast 20 minutes. Do not turn them — leave the cut faces to brown.
Roughly chop the walnuts and slice the garlic.
After 20 minutes, scatter over the walnuts and garlic and roast 5 minutes more. They go in last because they burn.
Out of the oven, squeeze over the lemon juice. Add the honey now if using, and toss.
Do not skip the drying step. It is the most common reason this dish fails. Water on the surface turns to steam before browning can start, and the sprouts go soft without colour. If you washed them, press them dry with kitchen paper.
They are not boiled because of the vitamin C. Raw Brussels sprouts hold 85 mg per 100 g — more than an orange's 53 mg. But vitamin C dissolves in water and degrades with heat, so boiling sends a good share of it down the drain. Roasting has no water, so it loses less.
Vitamin K is the opposite. There is 177 µg per 100 g, it is fat-soluble, and cooking barely touches it — the olive oil raises absorption. If you take warfarin, that becomes a caution rather than a benefit; see below.
Garlic and walnuts go in for the last five minutes because they scorch. Walnuts are 65% fat and turn bitter in ten minutes at 200°C. So does garlic.
The lemon goes on outside the oven. Both the acid and the vitamin C are heat-sensitive.
Choose small sprouts. Larger ones tend to hold more glucosinolates and taste more bitter. The sweetest come after frost, in late autumn and winter.
Vegetables
Moderate evidenceMore vitamin C than an orange, at 85 mg, and 177 µg of vitamin K. Cruciferous vegetables tracked with lower cardiovascular disease and mortality, but that is observational and not about Brussels sprouts specifically.
Nuts & seeds
Moderate evidenceWalnuts carry 9.1 g of ALA per 100 g, an order of magnitude beyond other nuts. But the rate at which ALA converts to EPA and DHA is very low.
Oils & fats
Strong evidenceCardiovascular events were 31 % lower in a randomised trial of 7,447 people. Against other vegetable oils, though, there was no difference.
Vegetables
Moderate evidenceThe evidence for garlic points to a modest drop in blood pressure and cholesterol. The trick is to crush it and wait ten minutes before it hits the heat.