Roast the beetroot by wrapping in foil and placing in a medium oven for about an hour (test with skewer).
Unwrap and allow to cool, peel and halve.
Marinate kangaroo fillets in oil, pepper and a pinch of salt (salt is optional), set aside for 20 mins.
If the fillets are quite thick, simply slice in half length ways for a thinner piece of meat.
Peel and dice potatoes, place in a pot of salted water and bring to boil.
Once boiling, add garlic, boil until potatoes are soft. Drain well and return to pot.
Add butter and milk and mash until fluffy.
Heat pan or BBQ grill until hot.
Sear fillets for 2-3 mins on each side.
Turn heat down and cook to liking (further 1-2 mins for rare, 2-3 mins for medium rare).
Allow kangaroo to rest for 5-10 mins before serving.
Fillets can be served either whole (if thinner pieces of meat) or can be sliced and arranged on plate.
Serve with beetroot and mash.