Rub chicken with salt and pepper; let rest 10 minutes.
Heat oil in skillet over medium-high; sear chicken 4-5 min per side until golden and cooked. Remove and set aside.
In same skillet, add oil, sauté onion until translucent (~5 min), then garlic and cumin until fragrant (~1 min).
Stir in ají amarillo paste; cook 2 min.
Add chicken broth, scraping browned bits; bring to simmer.
Pour in cream or evaporated milk; stir until smooth and slightly thickened.
Return chicken to pan, spoon sauce over and simmer 5 min. Taste and adjust seasoning; add sugar if spicy.
Garnish with cilantro; serve with rice, quinoa or plantains.
