Heat olive oil in saucepan over medium heat.
Saute onions in oil for several minutes or until golden and limp.
Sprinkle with curry powder and stir again.
Add lentils and water to cover plus a bit more (depending on how soupy -- or not -- you want it to be). Bring to a boil.
When boiling, reduce heat, cover, and simmer until just tender (do not overcook). Length of time will depend on what kind of lentils you're using.
Add cooked rice and tomatoes and bring back to up the boil to heat through.
Add more liquid if necessary (water or chicken or veggie broth will work here).
Stir in a couple tablespoons of balsamic or other vinegar, and adjust seasoning to taste with salt and pepper.
Stir in spinach or other green, and cook a couple more minutes or just until wilted.
Fry up or grill some sausages, and serve on top of hot lentil-rice stew.