Before adding ingredients to the slow cooker, heat a medium frying pan to medium-high heat with 1 tbs. of olive oil in the pan.
Pour the chopped onions and salt and pepper into the pan, and sauté for 5-10 minutes. Sauté the onions until they have caramelized. If your onions start to brown too much and it starts sticking to the pan, pour a little vegetable broth into the pan. Scrape the bottom of the pan with your spatula, as the broth will break up the browning at the bottom of the pan. This will also give the onions additional color and flavor.
Once the onions are caramelized, dump the onions into the slower cooker.
Then add 1 tbs. of olive oil into the frying pan again while the stove top is still on medium-high heat. Dump the chopped mushrooms in with salt and pepper and sauté for 5 minutes.
Dump the sautéed mushrooms into the slow cooker.
Dump in the celery, carrots, minced garlic, cumin, tomato paste, lentils, pinto beans, vegetable broth, green beans, rosemary, and maple syrup into the slow cooker.
Add 1 ½ tsp of salt and a lot of freshly cracked pepper. Stir to combine and secure the lid on.
Slow cook for 4 hours on high or 8 hours on low.
Once it’s done, stir in the chopped chard, lemon juice, lemon zest, and olive oil.
Serve hot with some bread and enjoy!