Adding lentils to minced beef dishes

[LifeInAHamsterWheel]

In an effort to increase fibre and just be a bit healthier, I add red lentils to things like bolognese, chilli con carne, shepherds pie etc but I'm wondering if I can add them to beef burgers and meatballs? If so, can I still use red lentils or is any other lentil better? Do they need to be cooked/soaked first? Thanks

I buy tins of green or brown lentils, give them a rinse and chuck them in, they hold up fine normally but sometimes need to add some breadcrumbs if it's a bit wet. Tins normally less than 80p

i put the green ones in lasagne and chilli- half mince half lentils and it tastes fine and it is healthier and cheaper