Preheat oven to 500°.
Combine 1/2 cup of broth, sugar, vinegar, and soy sauce in a small bowl. Place onion, garlic, and tomatoes in a 13 x 9-inch baking pan coated with cooking spray. Pour broth mixture over tomato mixture. Bake at 500° for 50 minutes or until vegetables are lightly browned.
Place tomato mixture in a blender. Add remaining 1/2 cup broth and half-and-half, and process until smooth. Strain mixture through a sieve into a bowl; discard solids. Garnish with cracked black pepper, if desired.