How to Make It
In a food processor, blend scallions, garlic, lime juice, 1 Tbsp. salt and 1/4 tsp. pepper. Coat chicken with mixture. Place in a ziplock bag. Seal and chill for at least 1 hour.
Warm oil in a skillet over medium-high heat. Pat chicken dry; brown on both sides, about 5 minutes. Remove to a plate. Reduce heat to medium; add 3 Tbsp. water. Scrape up browned bits from pan. Sauté onion and bell pepper until tender, about 5 minutes. Add jalapeño. Sauté 1 minute longer.
Stir tomato paste into 1 cup warm water. Stir into skillet with thyme. Put chicken in skillet. Bring to a boil, cover and simmer until cooked through, about 30 minutes. Remove chicken. Simmer sauce until thickened slightly, about 10 minutes. Serve.