1 teaspoon safflower oil
1 small onion, diced
10 ounces cremini mushrooms, sliced
3 cloves garlic, minced
1 1/2 teaspoons dried sage
1/2 teaspoon salt
1/2 cup yellow split peas
4 cups vegetable broth
1 1/2 pounds russet potatoes, peeled and cut into chunks
1/2 pound carrots, peeled and cut into chunks
2 heaping tablespoons thyme
1 cup water
1/4 cup all purpose flour
3/4 cup frozen peas
Preheat a 4 quart pot over medium-high heat. Saute the onions in the oil until translucent, about 4 minutes. Add the mushrooms, garlic, sage, salt, and pepper. Saute for 3 more minutes, until the mushrooms have released their moisture.
Add the split peas and broth, cover the pot, and bring to a boil. Let boil for about 5 minutes, then add the potatoes and carrots. Lower the heat and simmer 25-30 minutes, or until the split peas are tender and the potatoes and carrots are cooked. Stir occasionally.
In a measuring cup, mix the flour and water to dissolve into a slurry. Add the thyme, slurry, and frozen peas to the pan.
Cook uncovered for about 10 more minutes, stirring often. The stew should thicken. Taste for additional salt.