No, I haven’t got an Instapot. I alternate between the slow cooker and the hob - all depends on the recipe and how much time I’ve got.

I use the stock from my ham joint, some veg and lentils, once the root veg are softened the lentils are usually soft, I then decide whether I want chunky or smooth soup.

I find that red lentils get mushy too. I wonder if you get a different type of lentil in England than we do here? At any rate, have you tried an immersion blender to break them up?