Preheat oven to 180°C (160°C fan-forced). Combine tamari, garlic, ginger, chilli, honey, lime juice and sesame oil in a blender until smooth. Pour marinade over chicken and set aside for 20 minutes, turning once.
Drizzle oil over pumpkin and tomatoes in a small bowl and toss to coat. Transfer to a baking tray and bake in the oven for 25 minutes or until tender.
Lightly spray a grill pan with oil and heat. Remove chicken from marinade (reserve marinade) and sear in pan for 3 to 4 minutes on each side. Transfer to oven, pour marinade back over chicken and cook for an additional 10 minutes.
Remove vegetables from oven and toss through spinach.
Sprinkle veggies with balsamic vinegar, season with pepper and serve with chicken.

Tamari is a naturally brewed Japanese soy sauce that is slightly thicker than regular soy sauce and fermented without using wheat. You can usually find it in the health food section in the supermarket or health food stores.