Place the green bell pepper in a large pot with 1 tsp oil, and cook, stirring constantly, until peppers are slightly burnt.
Mix in tomatoes, onion, garlic, and the water. Season with salt, sugar and oregano. Bring to a boil, and cook 20 minutes, until tomatoes are soft.
Mix the milk and cornstarch in a small saucepan, and stir until smooth. Place saucepan over medium heat, and stir in remaining oil. Continue to cook and stir until thickened. Mix into the pot with vegetables.
Strain about 1/2 the vegetables from the soup and transfer to a blender. Blend until smooth, and return to the pot. Bring soup to a boil, reduce heat to low, and simmer 5 minutes.
Remove from heat, and let sit about 5 minutes before serving
