Preheat oven to 400 degrees. Prepare 2 baking sheets with foil. Thoroughly rinse produce and pat dry. Core and dice Roma tomatoes. Peel and cut red onion into thin strips. Zest and halve lime. Stem and coarsely chop cilantro. Halve and pit avocado. Scoop out flesh with a spoon. Cut avocado lengthwise into ¼" slices. Drain and rinse black beans.

Place poblanos on baking sheet. Brush with olive oil and bake for 15 minutes, or until soft. After removing, enclose foil around peppers so they can steam for 5-10 minutes, which will loosen the pepper's skin from the flesh. Skin, stem, seed, and slice pepper into thin strips. Brush both sides of eight tortillas with 1 tsp. olive oil each, then place on 2nd baking sheet, overlapping slightly. Bake for 10 minutes, or until crisp. Remove tortillas from oven and season with a pinch of salt and pepper.

Bring rice, 2 cups of water, and vegetable base to a boil in a medium pot. Cover, reduce to a simmer, and cook for 15 minutes, or until rice is tender. Remove from heat, season with a pinch of pepper, half the cilantro, and juice of half the lime. Set aside.

In a medium pan, place half the beans and ½ cup water over medium heat. Mash the beans with a fork while cooking. Cook for 5 minutes or until beans are warmed through and water is absorbed. Add the other half of the beans and cook for an additional 3 minutes. Season with a pinch of salt and pepper.

Spread a thin layer of beans on a tostada, then top it with sliced avocado, diced Roma tomatoes, strips of poblano pepper, and sliced red onion. Place another tostada on top and repeat the sequence of ingredients, finally topping with queso fresco. Garnish with lime zest and remaining cilantro. Repeat for second serving. Squeeze remaining lime juce to taste. Place a serving of rice next to the stacked tostadas and dig in!