There is an Regional Achievement (hubs) called "I like it hot" in Secret World: Legends. To get it, you need to eat a "Flamin' Hot Taco". How do you get one?
From the central Agartha hub, go to London. In London, go to the Haitian Market (south of the map). In the Haitian Square Market, you find a friendly monstrous trader called Dante. Dante sells Tacos - and a Hot Sauce.
Now, how to combine? You may have tried to use your Upgrade or Fusion tool, as you are used to. But this one works differently. Right behind Dante, you find some stack of dishes. Use them to open the Assembly window - which looks like the one people used in The Secret World. In this window, put tacos and hot sauce, click combine, and you get hot tacos.
Those are pretty hot, but not hot enough for an achievement yet.
Use the assembly window again, this time with hot tacos, and another bottle of hot sauce. The result will be tacos so hot they have you spitting flames - literally. Voila, your achievement! And some really hot tacos to go.