Smothered rissoles

Bahan-bahan (4 porsi)

• 1/2 large onion (, grated using standard box grater (Note 1))
• 1/2 cup panko breadcrumbs ((sub regular breadcrumbs, Note 2))
• 500 g / 1lb beef mince ((ground beef))
• 1 small zucchini (, grated)
• 1 small carrot (, peeled and grated)
• 1 large egg
• 1 large garlic clove (, crushed using garlic press or finely grated)
• 1/2 tsp dried thyme ((optional))
• 1/2 tsp oregano ((optional))
• 1/4 tsp black pepper
• 3/4 tsp cooking salt / kosher salt ((halve for table salt))
• 2 tsp Worcestershire sauce
• 2 tbsp olive oil (, for cooking)
• 30 g / 2 tbsp unsalted butter
• 1/2 onion (, sliced 5mm/0.2" thick)
• 2 g arlic cloves (, finely chopped)
• 200 g / 7 oz mushrooms (, sliced 5mm/0.2" thick)
• 3 1/2 tbsp flour ((plain / all-purpose))
• 2 cups beef stock / broth (, low sodium)
• 1/4 tsp cooking salt / kosher salt ((halve for table salt))
• 1/4 tsp black pepper
• 1 tsp Worcestershire sauce
• Mashed potato (or other starchy vehicle of choice)