Finely dice the yellow onion, zucchini, and red bell pepper, and mince the garlic clove.
Heat the olive oil in a large skillet or tagine over medium heat and sauté the onion and bell pepper until softened.
Stir in the garlic, zucchini, cumin, sea salt, and black pepper, cooking for 3 minutes until the zucchini is tender-crisp.
Add the harissa paste and nutritional yeast, stirring constantly for 1 minute to toast the spices and coat the vegetables evenly.
Pour in the vegetable broth and the drained, rinsed cannellini beans, bringing the mixture to a gentle simmer.
Reduce the heat to low and let the tagine thicken for 8-10 minutes, allowing the flavors to meld into a rich, fragrant sauce.
Remove from heat and serve in a shallow bowl, topped with a generous dollop of Greek yogurt and a sprinkle of fresh parsley.