Beer-marinated boerewors

Preheat the oven to 200°C.
Top and tail the beans then blanch them in a saucepan of boiling water before refreshing in cold water.
Toss the potato and onion cubes in half the butter, season and arrange on a baking tray. Roast for 25 minutes, or until golden and tender.
To make the béarnaise sauce, suspend a glass bowl over a saucepan of simmering water, add the egg yolk and vinegar and whisk until the mixture starts thickening. Gradually add the remaining melted butter, whisking continuously.
Sear the sirloin in a smoking-hot pan for 2 to 3 minutes a side, then transfer to a baking tray and finish off in the oven for 4 minutes. Allow the meat to rest for a few minutes before slicing it thinly.
Place a spoonful of the potato and onion mixture on a plate, arrange 4 to 5 slices of sirloin next to it and top with the green beans. Drizzle with the béarnaise sauce and serve immediately.
Cook's note: Namibian free-range sirloin is available exclusively from Woolworths. Read more about this healthy meat option here.