Sauté the onion and garlic: 

Heat the sunflower oil in a pan over medium heat. Add the onion and garlic and sauté gently without colouring (about 5 minutes).

Add the spices:

Sprinkle in the smoked paprika, cumin, and black pepper. Cook for 30 seconds to release the aromas.

Add the rest: 

Stir in the sugar, honey or syrup, mustard, Sriracha, ketchup, vinegar, water, and garum. Mix well.

Simmer briefly: 

Bring the sauce to a boil, then turn off the heat.

Cool and finish:

Let the sauce cool. Taste and, if needed, add a bit more garum to adjust saltiness or umami.