Try this as a salad dressing or as a marinade for pork, chicken, or fish. Guava paste is about an inch-thick block wrapped in cellophane in a 16-ounce package. It is sold in Latin markets and large supermarkets. Store any unused product in the refrigerator because it is easier to cut when chilled.
Combine first 3 ingredients in a small saucepan. Place over medium heat; cook 5 minutes or until guava paste dissolves, stirring frequently. Remove from heat. Add rice vinegar and dark sesame oil, stirring with a whisk until blended. Store in an airtight container in refrigerator up to 1 week.