White Bean and Sausage Ragout with Tomatoes, Kale, and Zucchini

olive oil

chopped onion

links chicken sausage, cut into (1/2-inch) slices

zucchini, quartered and cut into (1/2-inch) slices (about 2 cups)

garlic cloves, peeled and crushed

chopped trimmed kale (about 1/2 pound)

water

cannellini beans or other white beans, rinsed and drained

diced tomatoes, undrained

salt

freshly ground black pepper