In a small food processor add the avocado along with the tahini, lemon juice, water, cumin & salt. Set aside.
Reserve 8 prawns for garnish & chop the rest into small cubes.
To assemble, add lettuce leaves to glass bowls & spoon in the diced avocado. Squeeze some lemon over each glass.
Top with a dollop of seafood cocktail sauce.
Distribute the chopped prawns between the 4 glasses.
Top with piped avocado sauce.
Garnish with toasted pita triangle, remaining prawns, sliced avocado & some sumac/sesame seeds.