Salisbury steak meatballs with mushroom gravy

Bahan-bahan (4 porsi)

• 3/4 cup panko breadcrumbs ((Note 1))
• 1/2 onion (, peeled (brown/yellow))
• 500 g / 1 lb beef mince (ground beef)
• 1 g arlic clove (, minced)
• 1 egg
• 1 tbsp ketchup ((or Aussie tomato sauce))
• 1 beef bouillon cube (, crumbled (Note 2))
• 1/2 tsp Worcestershire sauce
• 3 tsp dijon mustard (OR 2 tsp dry mustard powder)
• 1 tbsp olive oil
• 2 tbsp / 30g unsalted butter
• 250 g / 8 oz mushrooms (, sliced)
• 1/4 tsp each cooking/kosher salt & pepper
• 2 g arlic cloves (, minced)
• 2 cups beef stock (, low sodium)
• 1/4 tsp each cooking/kosher salt & pepper
• 3 tbsp flour ((all purpose / plain))
• 2 tbsp water
• 2 tsp dijon mustard
• 2 tsp Worcestershire sauce
• Mashed potato ((or rice or pasta))
• Parsley (, finely chopped (optional))