Vegetable Paella

1 medium-size onion, chopped

1 red bell pepper, diced

8 ounces green beans, ends trimmed and cut into 1-inch pieces (2 cups)

1 can (28-ounces) plum tomatoes, drained and chopped

2 cloves garlic, finely chopped

4 cups vegetable stock or water

1 1/2 cups Valencia or other short-grain rice

1/4 teaspoon ground fennel

saffron threads or 1/4 teaspoon ground turmeric

1/2 teaspoon salt

1/2 teaspoon red pepper flakes

1 1/2 to 2 cups cooked or canned cannellini beans, rinsed and drained if canned

1 cup frozen peas, thawed