I'm wondering exactly what "pickled pork ribs" might be, whether the
pork is pickled in brine or vinegar. I haven't noticed anything like
this in my local supermarket's Mexican foods section. Maybe it's found
with the pickled pig's feet in a jar?

Costillas de Cerdo Adobada con Arroz ( Pickled Pork Ribs with Rice)
Ingredientes: (Ingredients
Para 4 personas (For 4 people)
4 tazas de arroz (4 cups of rice)
1 libra de costilla de cerdo adobada y partida en trozos pequenos
(1 pound of pickled pork ribs cut up in very small pieces, like diced)
4 cucharadas de aceite de oliva (4 tablespoons of olive oil)
1 cebolla picada (1 perforated onion)
2 dientes de ajo picados (2 cloves of perforated garlic)
5 tazas de caldo (5 cups of broth)
1 ramita de tomillo (1 sprig of thyme)
chile serrano picado (perforated serrano chile)

Preparacion: (Preparation

En una paellera, freir con 4 cucharadas de aceite de oliva, la cebolla
y el cerdo.

(In a paella pan, fry the onion and the pork in 4 tablespoons of olive
oil.)

Anadir el caldo, el tomillo, y el chile. Dejar cocer durante 20
minutos.

(Add the broth, the thyme and the chile. Let it cook for 20 minutes.)

Agregar el arroz. Cocinar primero a fuego fuerte y despues a fuego
suave. Se puede terminar en el horno para que no se queme.

(Add the rice. Cook over a high flame at first, and then with a lower
fire. You can finish cooking in the oven so it doesn't burn.)