Quick Vegetable and Navy-Bean Stew

I've made this stew for so long, I can't believe I haven't posted it until now.  The simple recipe is a photocopy from somewhere!  It makes for a great lunch on a chilly day and keeps well for leftovers.


1 Tbsp olive oil
1 small onion, chopped
4 small red potatoes, cut into 1/2-inch pieces
1 pound button mushrooms, trimmed and quartered
1/4 tsp dried thyme
salt to taste
1 Tbsp tomato paste
2 cups water
10 ounces spinach
1 can nay beans, drained and rinsed
1 Tbsp red-wine vinegar, optional
pepper

In a large nonstick skillet or heavy pan, heat oil over medium heat.  Add onion and potatoes; cook until onion is lightly crowned, 8 to 10 minutes.  Add mushrooms, thyme, and salt; cook, stirring often, until mushrooms are tender, 8 to 10 minutes.

Stir in tomato paste, and 2 cups water; cover, and cook until potatoes are tender, 8 to 10 minutes.  

Add half the spinach; cover, and cook until wilted, about 1 minute.  Add remaining spinach and beans; cook (covered) until heated through.  Stir in 1 tablespoon red-wine vinegar if desired.  Season with salt and pepper, and toss to combine.