Slow Cooker Vegetable Minestrone Soup

Name: Slow Cooker Vegetable Minestrone Soup
Ingredients: * 5 scallion, thickly sliced; * 3 carrot, sliced; * 3 rib celery, sliced; * 2 large garlic clove, chopped; * 1 28-oz can diced tomato; * 4-1/2 cup vegetable broth; * 3 thyme sprig; * 2 15-oz can chickpea, rinsed and drained; * 3 piece raw shan yao (an optional chinese herb); * 1 cup raw buckwheat groat, rinsed and drained; * sea salt and black pepper to taste; * 1/4 tsp dried oregano; * 10 oz fresh or frozen green pea; * 1 bunch asparagus, sliced on the diagonal into piece