In a medium bowl, whisk the lemon juice with the olive oil, coriander and cumin seeds, and crushed red pepper. Divide the marinade into thirds. Arrange the chicken in a shallow baking dish and top with one-third of the marinade. Cover and marinate in the refrigerator for one hour then preheat a grill and brush the grate with oil.
Meanwhile, in a medium saucepan, cover the bulgur with two cups of water. Bring to a boil and season with kosher salt. Cover, reduce the heat to low, and simmer until the bulgur is just tender, about 10 to 12 minutes. Fluff with a fork and cover the saucepan with a folded kitchen towel. Place a lid over the saucepan and let the bulgar steam until ready to use.
Drain the chicken and pat dry with paper towels; discard the used marinade. Season the chicken with salt and pepper. Wash the baking dish and pour one-third of the reserved marinade into the dish. Grill the chicken thighs covered over high heat, turning once until lightly charred and a meat thermometer inserted in the thickest part registers 160 degrees, about four minutes per side. Dip the chicken in the clean marinade in the baking dish, then transfer to a cutting board. Let it rest for 10 minutes, then slice into ½-inch thick pieces.
Grill the zucchini, squash, and red pepper until tender and lightly charred, about 10 to 12 minutes. Transfer the veggies to a carving board and thinly slice them. Fluff the bulger with a fork and fold in the grilled vegetables. Drizzle with some of the remaining one-third of marinade and season generously with salt and pepper.
Divide the bulgur and veggies between two shallow bowls and top with the sliced chicken. Garnish with parsley, mint, shaved parmesan, and toasted pine nuts as desired.