Heat ½ tbsp olive oil in a medium pan over medium heat. Add shallot and cook for 30 seconds. Add cauliflower, ½ tsp chili powder, ½ tsp cumin, and ¼ tsp salt. Heat for 6-8 minutes until florets start to soften. Scoop out cauliflower and place in a medium bowl.
In the same pan, add ½ tbsp olive oil, chickpeas, ½ tsp chili powder, ½ tsp cumin, and ¼ tsp salt. Cook for 5 minutes. Mash the chickpeas with the back of a spatula. Add water to the mixture and mix together until it forms a paste. Heat for 2-3 more minutes. Remove from heat.
Cilantro Lime Sauce: While the cauliflower and chickpeas are cooking, prepare the cilantro lime cream. Mix together Greek yogurt, lime juice, cilantro, water, and salt. Add more water to thin the sauce, if needed.
Char tortillas on the stovetop for a few seconds per side.
Assemble the tacos. Spread the chickpea mixture in the middle of each tortilla. Top with the cauliflower and lettuce. Drizzle the cilantro lime sauce over the taco toppings. Garnish with cilantro.