This easy weeknight dinner combines fresh ingredients and pantry staples in an inspired way: setting links of smoky Polish sausage atop saucy rice and lentils with wilted greens.
Heat oil in a large straight-sided skillet over medium-high. Prick kielbasa in a few places with a fork. Add to skillet and cook, flipping once, until browned in places, 5 to 7 minutes; transfer to a plate. Add onion to skillet; reduce heat to medium, season with salt, and cook, stirring occasionally, until golden, 5 to 6 minutes.
Stir in curry powder; cook 30 seconds. Add lentils and 2 1/2 cups water; bring to a boil, then cover, reduce heat, and simmer 10 minutes.
Stir in rice, tomatoes, and vinegar; season with salt and pepper. Return kielbasa and any juices to skillet. Cover; simmer over low until rice and lentils are just cooked through, about 15 minutes. Add spinach, cover, and cook until just wilted, 2 to 3 minutes. Stir spinach into rice mixture; season to taste. Slice sausage and serve.