1. Put a small pan on a medium heat and warm it for 1 min, then tip in the buckwheat. Toast for 2-3 mins, stirring, till it starts to smell nutty. Carefully pour in 350ml boiling water (it might splutter, so pour in a little at a time) and add a pinch of salt. Pop on a lid, bring back to the boil then turn the heat down and simmer for 15 mins till the buckwheat has absorbed all the water. Take off the heat and let the buckwheat sit in the pan, lid on, so it steams and finishes cooking.
2. While the buckwheat cooks, make the herb sauce. Peel and finely chop the garlic and scrape it into a small bowl. Pick the leaves off the sage and oregano sprigs. Finely chop the leaves and add them to the garlic. Add 1 tsp mustard to the bowl (you can keep the rest of the mustard to serve on the side).
3. Finely grate the zest from the lemon, add half to the garlic and set the rest aside for later. Squeeze the juice from half the lemon into the bowl with the herbs. Add 1 tsp olive oil, 1 tbsp cold water, a pinch of salt and pepper and stir together to mix. Taste and adjust the seasoning if you think it needs it. Set aside.
4. Prepare the veg: peel and finely chop the onion. Separate the kale leaves and slice the soft leaves off the thick, woody cores. Finely shred the leaves.
5. Rub 1 tsp oil into each venison steak and season them with salt and pepper. Put a frying pan on a high heat for 2-3 mins till it's smoking hot. Add the venison minute steaks and fry for 4-5 mins till browned underneath, then flip and fry for another 4-5 mins. This should give you a medium steak. For a more well-done steak (or if the steaks are thicker than 1cm), cook for an extra 1-2 mins on each side.
6. Pop the steaks on a warm plate or board and loosely cover with foil. Rest for 5 mins while you cook the veg.
7. Add the onion to the frying pan you cooked the steak in. Add 2 tbsp water and a pinch of salt and pepper. Fry, stirring, for 5 mins till the onion has browned. Add the kale and cook, stirring for 2-3 mins till the leaves have wilted. Take off the heat and stir in the remaining lemon zest. Add a squeeze of lemon juice and stir to mix.
8. Fluff the buckwheat with a fork and divide between 2 warm steaks. Add a wild venison minute steak to each plate with a heap of lemony greens. Serve with the herb.