Put zucchini, cumin, fennel, coriander and cayenne into a food processor and pulse until finely chopped but not mushy. Add cilantro and pulse a few more times to chop.
Place the garlic on a cutting board, sprinkle it with 1/2 teaspoon salt and use the side of your knife to mash it into a paste.
Add the ground turkey, garlic/salt and avocado to the food processor. Pulse until just combined. Since you can’t taste it here (you don’t want to eat raw turkey), if you find you need more or less seasonings make a note of it for next time.
Form into 4 burger patties.
Heat the grill to medium-high heat. Oil grill and cook burgers for 5 minutes on each side, or until cooked through.
Serve the burgers on lettuce leaves with sliced avocado, tomato, salsa and tahini dressing.
Notes
The recipe is delicious as written but I like a lot of spice so in I use:
1 1/2 teaspoons cumin
1 teaspoon coriander
1/2 teaspoon fennel
1/4 teaspoon cayenne