if adding stuff like the usual rice, carrots, potatoes or corn doesn't help, i've found that (with all those extra ingredients included) letting the lentejas overnight, and the next day putting them into a blender and then warming them up again can make them a lot easier to get through? if you end up not liking the texture, eating that with a side of bread or even making some fresh rice and mixing those two can end up being pretty good? just from my experience ofc but that's what's been working with me!