0.25 cups  Sweet Potatoes

1 tsp  Lemon Zest

0.3 cups  Lemon Juice

0.25 cups  Tahini

1 tbsp  Nutritional Yeast

1 tbsp  Dijon Mustard

2 tsp  Capers , plus 1tsp caper brine

Black Pepper

Watercress , to serve