Whisk together Tamari, balsamic, honey, garlic, fennel seed, red pepper flakes, lemon zest and juice and olive oil. Place chicken in marinade and preheat grill to medium-high. Marinade chicken 15 minutes, turning occasionally.
Parboil asparagus in 1 inch of boiling water for 2 minutes. Cold shock and drain well.
Grill chicken for 12 minutes, turning occasionally. Grill asparagus to mark evenly, 3-5 minutes. Slice chicken and layer with asparagus tips; top with scallions and drizzle with thinned out Harissa or Sriracha, and serve.