Sous-vide Beef Cheeks, Mashed Potatoes and Spinach

Sous-vide Beef Cheeks

• 700 g beef cheeks (4 cheeks, approx. 3 cm thick)
• 400 g ale
• 1 tsp salt
• 1 pinch ground black pepper
• 60 g celery, cut in pieces (2 cm)
• 50 g carrot, peeled, cut in pieces (2 cm)
• 60 g onions, quartered
• 1400 g water (approx. or enough to fully submerge bags but not higher than the maximum capacity of the bowl)
• 30 g lemon juice, freshly squeezed (see tip)
  or 1 tsp ascorbic acid powder

Parmesan Mashed Potatoes and Assembly

• 30 g Parmesan cheese, cut in pieces (2 cm)
• 1000 g floury potatoes, peeled, sliced (2 mm)
• 280 g water
• 5 g salt, plus 1-2 pinches to taste
• 2 Tbsp unsalted butter, plus 30 g diced
• 1 Tbsp Dijon mustard
• 2 - 3 pinches ground black pepper, to taste
• 1 Tbsp cornflour, mixed with 1 Tbsp water
• 1 pinch ground nutmeg
• 1 garlic clove
• 20 g olive oil
• 150 g fresh spinach leaves