Grilled Beef Heart with Radicchio and Orange

Ingredients

• 700 gm beef heart
• 200 ml red wine
• 1 tbsp thyme
• 1 tsp finely grated garlic
• 200 ml freshly squeezed orange juice
• 20 gm caster sugar
• 80 ml chardonnay vinegar (1/3 cup)
• 100 ml olive oil, plus extra for rubbing
• 1 small fennel bulb, thinly sliced on a mandolin, fronds reserved
• 1 large head of radicchio, leaves separated
• 1 orange or blood orange, peeled and sliced into rounds
• 80 gm walnuts