Place chicken in a shallow dish and season with salt and pepper.
In a food processor, process chilies, garlic, oregano or marjoram, bay, lime zest and juice, paprika and about 1/4 cup olive oil into a paste. Slather all over the chicken pieces, coating them evenly. Chill several hours or overnight.
Heat 1 tablespoon of olive oil in a skillet over medium-high heat.
Add cumin seeds and swirl a few seconds to toast then add chicken pieces and lightly brown, 10 minutes.
Sprinkle sugar over the chicken and add stock. Partially cover and cook 10 minutes more.
Toss with mint and cilantro, and serve with mashed blue potatoes alongside.