The day before, in a bowl, combine Greek yogurt and Tikka Masala paste and add chicken. Marinate overnight. The next day, heat grill pan on the stove top.
Brush the naan bread lightly with olive oil and grill both sides till warmed through.
Remove bread to your service plate. Brush the zucchini slices with olive oil, season with salt and pepper, and grill both sides till just cooked through. Layer grilled zucchini onto grilled naan bread. Top zucchini with layers of thin sliced tomato. Wipe off excess marinade from chicken. Add a touch of oil to the hot grill pan and grill chicken till cooked through. Top your sandwich off with the chicken slices. Sprinkle sandwich with the crumbled feta cheese. Drizzle the sandwich with the Sriracha Hippy-Shake. Eat proudly with a knife and fork.
For the Sriracha Hippy-Shake:
In a bowl, combine mayonnaise, Sriracha and lemon juice. Thin with water to a milkshake consistency.