Anchovy and Garlic Tuna with Tomato and Oregano

Ingredients

• 1 kilogram tuna fillet, trimmed, skinned
• 3 clove garlic, sliced thinly
• 1/4 cup firmly packed fresh oregano leaves
• 8 drained anchovy fillets, halved
• 1/4 cup (60ml) olive oil
• 1 large brown onion (200g), sliced thinly
• 4 large roma tomatoes (360g), seeded, chopped coarsely
• 1/4 cup (60ml) balsamic vinegar
• 2 tablespoon dry white wine
• 1/4 cup (60ml) fish stock
• 1 tablespoon drained baby capers, rinsed
• 1/4 cup coarsely chopped fresh basil
• Feta and black olive mash
• 1 kilogram coarsely chopped potato
• 2 tablespoon olive oil
• 2/3 cup buttermilk, warmed
• 200 gram finely chopped feta
• 1/2 cup thinly sliced black olives