In a medium bowl, combine all ingredients: doenjang, gochujang, sesame oil, honey, sesame seeds, minced garlic, and sliced onion.
If using, add the chopped walnuts and diced apple.
Mix all ingredients thoroughly until well combined and smooth. This should take about 1 minute.
Transfer the sauce to a serving bowl.
If desired, garnish with sliced green onion, minced green chilies, and additional sesame seeds.
Serve immediately as a dipping sauce for Korean barbecue, vegetables, or lettuce wraps.
Storage:Store unused ssamjang in an airtight container in the refrigerator. For food safety, consume within 3-5 days, though it may last up to 1-2 weeks when properly stored.