Fish with herbed chickpea puree

Ingredients (4 servings): 1 tablespoon olive oil 1 brown onion, finely chopped 1 garlic clove, crushed 1½ teaspoons ground cumin 1 cup Chicken Stock 2 x 420g cans chickpeas, drained, rinsed 1 tablespoon lemon juice ½ cup parsley, roughly chopped 4 pieces fish fillets (such as hake) 2 cups baby spinach 2 tomatoes, chopped  …