Ingreadient

• 1 1/2 pounds beef oxtail, cut into pieces
• 1 large onion, quartered
• 2 cloves garlic, chopped 1 teaspoon salt
• 1/2 teaspoon ground black pepper, or to taste
• 1 large eggplant, cut into 2-inch chunks
• 1/2 head bok choy, cut into 1-inch pieces
• 1/2 pound fresh green beans, trimmed and snapped into 2-inch pieces
• 1/4 cup peanut butter, or as needed to thicken sauce