Heat a little bit of coconut or olive oil in a large saucepan over high heat; when pan is sizzling hot, add and sear the pieces of meat until they are nice and golden on all sides.
Add onions, garlic, salt and pepper; lower heat to medium and continue cooking until the onions are softened.
Add ground mustard seeds (or dry mustard), dried herbs, white wine vinegar,1 cup of water and chopped tomato. Stir until well combined.
Cover loosely, lower heat and simmer, stirring from time to time, until the liquid is almost completely evaporated; add another cup of water and repeat the process until you’re left with very tender pieces of beef and close to no liquid at the bottom of the saucepan. Turn off the heat and reserve.
Preheat a large non-stick skillet over medium-high heat and add the aubergine slices in a single layer. Sprinkle with salt and pepper and cook until tender, flipping once, about 2 minutes per side. You might have to cook them in 2 or 3 batches, depending on the size of your skillet. Remove aubergine slices from pan and keep warm while you continue working on the rest of the vegetables.
Put skillet back over the heat source and add zucchinis and mushrooms; cook for a one or two minutes, just to soften them up a little bit.
Add reserved meat mixture, tomatoes and fresh basil and stir delicately until all is well combined.
Divide the aubergine slices between 2 serving plates and arrange them in a circular fashion.
Top with meat mixture, garnish with a few additional basil leaves and serve immediately.