Chop and sauté onions with oil and curry spices of choice; add red lentil, rice or potato, lots of broth; simmer. Salt.
Eat with plain yogurt, parsley, raw cabbage half wilted in the bottom of the bowl. Lentil soup definitely wants some greens, and I love cabbage.
Speaking of cabbage:
The easiest cabbage business
Chop cabbage very finely. Chop more veg if you want them: mine are carrots and peeled broccoli stems. See, you should definitely keep your stems. Sautée quickly with neutral oil and a pinch of salt, add a splash of water and some sriracha sauce, then slap on the lid to steam. Give it a minute. Off heat, to keep pepper fumes present instead of evaporating, add a little more sriracha. Stir, add sesame seeds, eat.
Leftovers are the perfect fodder for fried rice or egg mess.