Heat a couple tablespoons of cooking oil in a sauté pan and add chopped sweet potatoes. Cook for about 10 minutes, until softened. Toss in garlic and cook until fragrant. Meanwhile, warm beans in a small saucepan on the stove.
To make the dressing, combine all the ingredients in a small blender and mix until smooth.
To assemble tacos, place sweet potatoes and beans on warm tortillas and drizzle with tahini lemon dressing.
Notes
Store leftovers and dressing in airtight containers in the refrigerator.