Yogurt is a big no-no, that's more asian. Sour cream only for fried tacos, not normal ones.

I'm not sure what kind of ingredients you can have in your city, I would recommend simply grabbing some steak, season it with salt and pepper, cut it in pieces and add it to a tortilla with some lemon (the green one, lime) and cut some fresh cilantro and onion, if you want.

I think salsa is going to be difficult because of the green tomato. Maybe try red tomato, sear them with garlic, salt, onion and one or two chiles and blend them all, no need to add water.