Place soybeans in small saucepan and cover with water. Bring to a boil. Lower heat to a simmer and cook, uncovered, 30 minutes. Remove from heat and drain.
Return the soybeans to the pot and add soy sauce, agave, sesame oil, and garlic. Stir to blend. Place over medium heat and bring to a simmer. Cover and allow to simmer over low heat for 30 minutes, stirring occasionally.
Uncover and stir a few times. Allow to continue simmering until sauce becomes thick and syrupy, about 10 minutes. Beans will still be a bit firm when done cooking.