Mulching is certainly the best natural answer to the problem of weeds and can be practiced even if you do a direct seeding and not a transplant. There are several ways to mulch your lentils, or your chickpeas.
The first hypothesis is to use straw, which I recommend if you grow on a small scale. The concept is to sow your legumes, let the seedlings grow and only once these are developed put straw to mulch all around the seedlings. This method has the advantage of being practically at no cost, moreover the straw is well breathable and then biodegrades in the soil. The disadvantage is that some grass will form before you put the mulch, which you will have to tear off, and it takes time to spread the straw.
The pre-perforated mulching sheet
A faster method and therefore more suitable for large crops is to use a mulch cloth. There are pre-perforated sheets, which are undoubtedly the most comfortable solution. You will obviously have to choose a cloth that has the right distance between the holes and that has a hole large enough to allow the sprout to come out easily. Alternatively, you can also drill the sheet yourself, with the size you want, perhaps using a specially built tool: a very simple sharp metal circle for not very resistant sheets, red-hot for plastic sheets.
I hope I was helpful, a greeting and good crops!