Creating Singapore Chili Prawns is straightforward if you follow these detailed steps:

1. Prepare the Prawns: Rinse the prawns under cold water and pat them dry with a paper towel.
2. Heat the Oil: In a large skillet or wok, heat the vegetable oil over medium-high heat.
3. Sauté Aromatics: Add minced garlic and chopped onions to the skillet. Sauté until fragrant and the onions are translucent.
4. Add Chili: Stir in the chopped chili and cook for another minute. You can adjust the amount based on your spice preference.
5. Mix Sauce: In a bowl, combine tomato sauce, chili paste, ketchup, sugar, and soy sauce. Stir until well mixed.
6. Cook Prawns: Add the prawns to the skillet and stir-fry for about 3-4 minutes or until they turn pink and opaque.
7. Add Sauce: Pour in the sauce mixture and bring to a simmer. Let it cook for a couple of minutes to allow the flavors to meld.
8. Thicken Sauce: Stir in the cornstarch mixture to thicken the sauce slightly. Cook for another 1-2 minutes, stirring constantly.
9. Garnish and Serve: Remove from heat and garnish with fresh coriander. Serve with lime wedges on the side.

These steps will guide you through creating this incredible dish with ease.