Heat olive oil in a large frying pan over medium heat.
Add onions, carrots, bell peppers, and salt. Cook for 10-15 minutes until softened.
Stir in garlic and oregano, cooking for another 5 minutes on low heat.
Transfer the vegetables to a blender, add canned tomatoes, sugar, black pepper, and food coloring (if using), and blend until smooth.
Return the sauce to the pan, bring to a simmer, and keep warm.
For the "fingers," cut small onion squares for nails and prepare hotdogs by cutting them in half and making indentations.
Simmer the hotdogs and onions in water for 5 minutes, then attach the onion "nails" with tomato sauce.
Cook pasta in salted water, drain, and toss with sauce. Serve with the sausage fingers nestled in the pasta.