In a saucepan, soften onion and garlic in oil. Add sauce, bring to a boil, and simmer for about 5 minutes. Add basil and adjust seasoning. Keep warm.
Preheat oil in the deep fryer to 190 °C (375 °F). Line a baking sheet with paper towels.
Place flour in a large bowl and eggs in another bowl. Combine breadcrumbs in a third bowl.
Flour the ravioli and shake to remove any excess. Dip in egg mixture and drain. Press in crumb mixture to coat.
Fry twelve ravioli at a time in oil for about 2 minutes or until golden brown. Drain on the baking sheet. Season with salt. Serve immediately with marinara sauce or freeze. Ravioli and sauce should be frozen separately.