Avocado and Shrimp Tartare with Avocado Ginger Dressing

Name: Avocado and Shrimp Tartare with Avocado Ginger Dressing
Ingredients: Tartare; 2 ripe but hard avocados; 1 1/2 cups cooked prawns or fresh (or smoked) salmon; 2 medium red onions; 1 teaspoon grated fresh ginger; 1 bunch cooked green asparagus; 3 ripe but hard tomatoes; 1 lime; 1 tablespoon fresh coriander; 2 pinches Piment d'Espelette or Chilli powder; 1 cup Cherry tomatoes for decoration; salt; Avocado and ginger dressing; 1 ripe avocado; 1 inch fresh ginger (grated); 3 tablespoons Greek yogurt; 2 tablespoons Extra Virgin Olive oil; salt & pepper to taste