Yes, Heracleum species and yes, you MUST be absolutely sure which plant you have before eating it!! In Norway, we have a giant hogweed which is very slightly different from H. mantegazzianum. It has invaded the arctic
city Tromso at near to 70 deg N...it looks totally out of place there... For many years botanists couldn't decide which species it was or whether it was a hybrid, but about 3 years ago they decided it was H. persicum (difficult even for botanists to tell apart from mantegazzianum which is also found here). At about the same time I had a group visiting my garden including an Iranian woman and seeing I was growing other Heracleum species proceeded to tell us that she collected seed of H. persicum locally every autumn as a spice and that in Iran they even use the young shoots as breakfast food! All were astounded....the following year two of us tried it and very good it was too like other Heracleums.... So, yes, I would be surprised if H. mantegazianum couldn't be used similarly....ordinary people couldn't tell the difference. Ironically, Iranian shops in Norway were importing seed of this "invasive" unwanted and according to the authorities poisonous plant - and, yes, you really have to be careful handling this plant as you can be severely burned by the combination of plant juices in sunlight! Much more about the Hogweeds in the book, probably the most important genus of plants traditionally use for food!
Tromso Palm (as it's called) in Tromso: