Herby Venison, Beef & Currant Burger

• In a small microwave-safe bowl, combine onion, the white wine vinegar
and a good pinch of sugar and salt.
• Microwave onion until softened, for 30 seconds. 

• In a large frying pan, heat a drizzle of olive oil over medium-high heat. 
Cook patties until just cooked through, 4-5 minutes each side (cook in 
batches if your pan is getting crowded).
• Meanwhile, halve, then toast or grill burger buns to your liking.
• Drain pickled onions.
• In a second large bowl, combine cucumber, radish, feta (see ingredients), 
mixed salad leaves, a generous squeeze of lemon juice, half the pickled 
onion and a drizzle of olive oil. Season to taste.