Alos Palsar L1.5 Mosaic workflow

Hi, hope you all doing well. I normally use Erdas Imagine MosaicPro, for decided to try SNAP and liked the workflow for working with Alos Palsar L1.5 data.

I’m trying to generate a DEM for a square shaped area that lies between 6 Alos Palsar grids. Its a relative small area of 80x80km. In Erdas Imagine I would start by creating a AOI for this area and then mosaicing only this aoi. In Step I couldn’t find this option and the process of mosaicing 6 grids for then subseting the result takes an eternity. How is this done in SNAP?

Thank you.

There is a SAR Mosaic operator which lets you do that.
However, you need Level 1.1 data for interferometry.