XTE J1810 - 197 was the first ever magnetar which was found to emit transient radio emission .
It has recently undergone another radio and high-energy outburst .
This is only the second radio outburst that has been observed from this source .
We observed J1810 - 197 soon after its recent radio outburst at low radio frequencies using the Giant Metrewave Radio Telescope .
We present the 650 MHz flux density evolution of the source in the early phases of the outburst , and its radio spectrum down to frequencies as low as 300 MHz .
The magnetar also exhibits radio emission in the form of strong , narrow bursts .
We show that the bursts have a characteristic intrinsic width of the order of 0.5 - 0.7 ms , and discuss their properties in the context of giant pulses and giant micropulses from other pulsars .
We also show that the bursts exhibit spectral structures which can not be explained by interstellar propagation effects .
These structures might indicate a phenomenological link with the repeating fast radio bursts which also show interesting , more detailed frequency structures .
While the spectral structures are particularly noticeable in the early phases of the outburst , these seem to be less prominent as well as less frequent in the later phases , suggesting an evolution of the underlying cause of these spectral structures .