I was just looking at our hob:

Strange wiring arrangement:

There is a flexible cable hardwired into the bottom of the hob with 5 cores

L1
L2
N1
N2
E

It is then up to the insaller / consumer to decide on 1 of 3 ways of hooking it up

Either:
16A - 400V
L1 - L1
L2 - L2
N1+N2 - N
E - E

2 X 16A 230V (2 seperate 16A MCBs or fuses)
Circuit 1:
L1, N1
Circuit 2:
L2, N2
E - protective earth.

Or 32A 230V (which is how it is wired)

L1+L2 connected to L
N1+N2 connected to N
E - protective earth.

feeding back to 1 X 32A breaker for the hob.
(the oven has its own 32A circuit seperately connected)

It's a French branded cooker (De Detrich)

I presume in France it would just be plugged in with a 3 phase plug?