Cut the Onion Nails: Cut 16 small squares from the onion and set them aside. These will become the fingernails for the hot dog fingers, because Halloween dinner should apparently require tiny vegetable nail art.
1 large yellow onion
Chop the Sauce Vegetables: Chop the rest of the onion. Finely chop the carrot and red bell pepper so they soften quickly and blend smoothly into the sauce.
1 carrot, 1 red bell pepper
Cook the Vegetables: Heat the olive oil in a large skillet over medium heat. Add the chopped onion, carrot, red bell pepper, and ½ teaspoon salt. Cook for 10 to 15 minutes, stirring often, until the vegetables are soft.
1 tablespoon olive oil, ½ teaspoon salt
Add Garlic and Herbs: Add the sliced garlic and dried oregano. Cook for 2 to 3 more minutes over low heat, just until the garlic smells fragrant and does not burn.
4 garlic cloves, 1 teaspoon dried oregano or Italian seasoning
Blend the Red Sauce: Transfer the cooked vegetables to a blender. Add the diced tomatoes, sugar, black pepper, and red food coloring if using. Blend until smooth.
1 28- ounce can diced tomatoes, 1 teaspoon sugar, ¼ teaspoon black pepper, 3 to 5 drops red food coloring
Warm the Sauce: Pour the sauce back into the skillet and bring it to a gentle simmer. Keep it warm while you make the hot dog fingers and cook the pasta.
Cut the Hot Dog Fingers: Cut each hot dog in half. On the cut end of each piece, make three shallow cuts about one-third of the way up to look like knuckles.
8 fully cooked hot dogs or frankfurters
Make the Fingernail Space: On the rounded end of each hot dog piece, carefully slice off a small flat square where the onion fingernail will sit. Do not cut too deep, or the finger will look like it had an even worse night than planned.
Heat the Fingers: Bring a small saucepan of water to a gentle simmer. Add the hot dog fingers and onion nail pieces, then cook for about 5 minutes, until the hot dogs are heated through and the shallow cuts open slightly.
Add the Onion Nails: Remove the hot dog fingers and onion pieces from the water. Use a tiny dab of red tomato sauce to stick one onion square onto each fingernail space, pressing gently so it stays in place.
Cook the Pasta: Bring a large pot of water to a boil. Add 1 tablespoon kosher salt, then cook the pasta for 1 minute less than the package directions.
14 ounces penne, 1 tablespoon kosher salt
Save Pasta Water: Scoop out about ½ cup of pasta cooking water before draining. Drain the pasta and return it to the pot.
½ cup reserved pasta cooking water
Sauce the Pasta: Add several spoonfuls of the red sauce to the pasta and stir gently over low heat. Add a splash of reserved pasta water if needed to loosen the sauce, then add more sauce until the pasta is coated to your liking.
Serve the Pasta: Spoon the red pasta into bowls and nestle the hot dog fingers into the pasta. Let them peek out just enough to look disturbing, because subtlety is not the point of Halloween dinner.