In a blender, add the tomatoes and 1/4 cup cucumber and purée until smooth. Set aside. In a large saucepan over medium-high heat, heat olive oil. Add the onion and cook until translucent — about 4 minutes. Reduce heat to medium, stir in the garlic, and cook for 2 minutes. Slowly add puréed tomato mixture, bell pepper, salt, and black pepper and stir to combine. Continue to cook for 35 minutes. Remove from heat and stir in the hot sauce and parsley. Serve hot, garnished with the sour cream, chimichurri sauce and remaining cucumber.