Heat olive oil in a sauté pan over medium-high heat. Add diced onion and jalapeño, sautéing for about 5 minutes until the onion is soft and translucent.
Add minced garlic to the pan and continue to cook for 1-2 minutes until the garlic is fragrant.
Transfer the sautéed mixture to a blender. Add vegetable stock, green chilies, cumin, salt, and black pepper.
Puree the mixture until smooth, ensuring there are no chunks left for a consistent sauce texture.
Taste the sauce and adjust seasoning with additional salt, pepper, or cumin as needed to suit your preference.
The sauce is now ready to be used immediately, or it can be stored in the refrigerator for up to 4 days or frozen for up to 3 months.