Check your avocado is ripe before starting this recipe (see cooking tip). Halve the cucumber lengthwise, then scrape out the seeds using a teaspoon. Finely chop the cucumber and tomato. Pick the mint leaves, discarding any large stems. Finely chop the parsley, including the stems. Crush or finely chop the garlic. Scoop out the avocado into a bowl or jug.
Step 2 — Make dressing
Add the mint, garlic, half the parsley, 1 tbs extra virgin olive oil, 2 tsp white wine vinegar and 80ml (⅓ cup) water to the avocado. Blend until smooth with a stick blender (if you prefer, you can make the dressing by hand; finely chop the mint and mash the avocado flesh with a fork, then stir in the rest of the ingredients). Taste, then season with salt and pepper.
Step 3 — Soak couscous
Put the couscous in a large heatproof bowl, pour over 200ml boiling water and cover with a plate. Stand for 5 mins or until the water is absorbed.
Step 4 — Toast pistachios
Meanwhile, put the pistachios in a cold medium frypan over medium heat. Toast, tossing, for 3-4 mins until evenly golden. Remove from the pan and cool slightly, then coarsely chop.
Step 5 — Fry falafel
Heat 1cm oil in the same pan over high heat until the oil is shimmering. Fry the falafel, turning regularly, for 2 mins or until golden. Remove from the pan with tongs and drain on paper towel.
Step 6 — Make couscous tabouleh
Fluff the couscous with a fork, then add the cucumber, tomato, remaining parsley, 2 tsp extra virgin olive oil and 2 tsp white wine vinegar. Stir to combine, taste, then season with salt and pepper. Divide the couscous tabouleh and falafel among bowls. Drizzle with the green goddess dressing and scatter with the pistachios to serve.