Step 1

Mix garlic, soy sauce, miso, curry powder, ginger, and 1 Tbsp. oil in a small bowl; set aside.

Step 2

Slice chicken breasts crosswise into ½"-thick strips. Season with salt and sprinkle with sugar. Heat 1 Tbsp. oil in a large nonstick skillet over medium-high. Cook chicken in a single layer, undisturbed, until well browned, 2–3 minutes. Turn and continue to cook just until exterior of chicken is opaque (it won’t be cooked through and the second side won’t get much if any color, and that is fine!), about 30 seconds longer. Transfer to a plate.

Step 3

Cook beans and remaining 1 Tbsp. oil in same skillet over medium-high heat, tossing often, until beans are bright green and lightly charred in spots, about 2 minutes. Transfer to plate with chicken. Reduce heat to medium. Add reserved curry paste and cook, stirring constantly, until paste darkens and garlic softens, about 1 minute. Add peas and ½ cup water. Return chicken and beans to skillet and cook, tossing occasionally, until sauce is reduced by more than half and thickens, 2–3 minutes.

Step 4

Transfer chicken and vegetables to a platter. Top with scallions.