I make this whenever I need some comfort food, its very comfy. You need is a cup of lentils, two-three cups of broth, a few pieces of celery, two carrots, 1/2 of an onion, and some garlic cloves, though the veggies are optional. You can pretty much use whatever you have available, frankly.
First, wash the lentils. Then place them in the pot with two cups of water. Boil it, then turn down the heat. Cook the lentils until most of the water is evaporated (~20-30 min). They should be chewy, but not hard. While you wait, you can chop the vegetables.
Next, add two cups of broth and a cup of water (or three cups of broth). Add in the carrots and garlic immediately. After 5 minutes, add the celery and onion. Cook everything until most of the water evaporates (20-30 min). Drain and serve.
You can eat them as is, pair them with another meal, put them in a soup, lots of options. Very filling too.
Unrelated but this reminded me of when I was 9 or 10, my mom took me into the kitchen and said, "I will teach you how to cook so if I die, you won't starve." I was freaked out as a child but its pretty funny looking back.
Sorry for amerifat measurements, you'll have to convert them.