To make the spinach: In a large skillet, heat olive oil. Add onion and garlic; sauté 4 minutes. Add tomatoes, soy sauce, ginger, and hot sauce; simmer 5 minutes. Add spinach; bring to a boil. Remove from heat and keep warm.
In a dish or resealable plastic bag, place calamari, lemon juice, salt, and pepper. Toss to coat calamari. Marinate 10 minutes.
Thread six 12-inch skewers with calamari. Brush with sesame oil. Place skewers in centre of cooking grate. Grill 4 minutes, turning once halfway through grilling time. Serve skewers on warm Asian spinach.