Classic Terribly confused about leveling professions

I just followed some guides that got me to level 305 in Engineering and 300 in Mining, concluding with Dark Iron Ore mining and smelting.The next step they say is mining and engineering in Hellfire Peninsula. They tell me to visit my trainer and learn Master Engineering to advance further. I visited Lebowski in Honor Hold and wasn't presented with any new options, other than learning Outland Mining.I attempted to craft about 20 or so of Handful of Fel Iron Bolts and didn't get any Engineering progress (aside from Outland Engineering).What do I do to advance to further levels of Engineering? What am I doing wrong?(Not in Classic, by the way) via /r/wow https://ift.tt/2MIzvy8