Heat the oil in a large nonstick skillet over medium heat.
Add the chopped onion and garlic and cook until softened, about 2–3 minutes.
Add the ground turkey and crumble it with a spatula; cook until no longer pink, about 6 minutes.
Stir in the chili powder, ground cumin, ground coriander, tomato paste, water, and salt to taste; bring to a gentle simmer and reduce heat to keep warm for serving.
Preheat the oven to the broil setting. Place the tortillas on a middle oven rack or an oven-safe rack and broil until the bottoms begin to brown and crisp, then flip and broil the other side; watch closely to avoid burning.
Spread each warm tortilla with warmed refried beans, then top with chopped lettuce.
Divide the turkey mixture among the tortillas, sprinkle with shredded cheese, then scatter halved tomatoes and sliced black olives over the top.
Serve immediately with guacamole, sour cream, and salsa as desired.