1. Combine the beans and salsa in a medium saucepan and warm over medium heat, stirring occasionally, while you make the salad and prepare the tortillas.
2. Combine the cabbage, carrot, onion, and cilantro in a medium bowl. Combine the olive oil, lime zest and juice, jalapeños, garlic, and salt in a small bowl and whisk together until fully emulsified. Pour dressing over cabbage mixture and mix until thoroughly coated. Set aside.
3. Heat a large skillet over medium-high heat. When the pan is hot, add 1 teaspoon of coconut oil, reduce heat to medium, and fry two corn tortillas for about 20 seconds, until bubbling, before flipping and cooking for another 20 seconds on the other side. Tortillas should be almost crispy when done. Drain the tortillas on a paper towel. Repeat for each tortilla, adding a teaspoon of coconut oil for each batch. If the pan starts smoking, remove from heat and allow the pan to cool. Use a paper towel to wipe out the pan before frying the next tortilla.
4. Set the oven to broil and move the rack to the top level. Arrange tortillas on a baking sheet in sets of two, with the two tortillas overlapping. You will have four sets of overlapping tortillas. Top each tortilla with ¼ of the bean mixture and ¼ of the shredded cheese. Place under the broiler until cheese is melted and starting to bubble, 3-4 minutes.
5. While the tostadas are under the broiler, add the romaine to the cabbage salad and toss until well coated with the dressing.
6. Remove the tortillas from the oven and place one set of overlapping tortillas in the center of a dinner plate. Layer ¼ of the avocado slices on top of the cheese and pile ¼ of the romaine-cabbage salad on top of each tostada. Repeat with the remaining tostadas and serve immediately.