Empty the tomato paste into a small saucepan. Fill the can with water and add it by small doses to the tomato paste, stirring well after each addition. When the can is empty, fill it again halfway and repeat the procedure. Add parsley, basil and oregano. Mix in garlic and onion powder according to taste. Cover, simmer on low heat for about 15 minutes. Taste the sauce, and adjust the seasoning if necessary. Re-cover and simmer for another twenty minutes, stirring occasionally.