Tip the pearl barley into a small pan and pour in enough water to cover it by a few cms. Add a pinch of salt. Cover, bring to the boil, then turn the heat right down and simmer for 15-20 mins till the barley is tender.
While the barley cooks, peel and crush the garlic. Finely chop the rosemary leaves. Place the venison steaks in a dish and pierce a few times with a fork. Rub in the garlic and rosemary with a pinch of salt and pepper and 2 tsp olive oil. Set aside to marinate.
Put half the blueberries in a small blender. Add the juice of half the lemon, 2 tsp olive oil and a good pinch of salt and pepper. Blitz to make a smooth, thick dressing. No blender? Crush the blueberries with a fork to make a pulp, then whisk with the lemon juice, oil and seasoning. Set the dressing to one side.
Peel the red onion and finely slice it. Slice the skin and white pith off the orange and slice the orange flesh into segments.
Place the remaining blueberries, the orange and baby leaf spinach in a bowl and set aside.
Heat a griddle or frying pan over a high heat for 2-3 mins till smoking hot. Add the venison steaks and fry for 3-5 mins on each side, or longer if you have steaks that are thicker than 3cm, or if you prefer well done steaks. Lift the venison steaks out of the pan and pop on a warm plate. Loosely cover with foil and set aside to rest for 5 mins.
Add the onion to the frying pan and sizzle for 5 mins till lightly charred. Scoop out of the pan and add to the bowl of salad.
The barley should be ready. Drain it and add to the bowl. Add half the dressing and toss to coat the veg and barley. Heap the salad up on 2 warm plates. Slice the venison and lay on top of the salad. Spoon over the last of the dressing to serve.