Slow Cooker Beef Stroganoff

Bahan-bahan (6 porsi)

• 1.75 kg / 3.5lb beef chuck or other stewing beef (, cut in 4cm / 1.5” cube (Note 1))
• 1.5 tsp each salt and pepper
• 2 tbsp oil
• 20 g / 1 tbsp butter (, unsalted)
• 1 large onion (, halved then sliced into 1 cm / 2/5" slices)
• 4 g arlic cloves (, minced)
• 7 tbsp flour (, plain / all purpose)
• 4 tbsp Dijon Mustard
• 1 litre / 1 quart beef stock/broth (, reduced salt)
• 1 1/2 cups sour cream (, full fat best)
• 3 tbsp / 45 g butter (, unsalted)
• 700 g / 1.2 lb mushrooms (, sliced into 0.5cm thick slices)
• 3 g arlic cloves (, finely minced)
• 1/2 tsp salt and pepper
• Pasta, wide egg noodles, mashed potato
• Chives for garnish