In a 2 quart microwave safe dish, toss onion with oil. Place garlic in the center. Cover; microwave on high 5 minutes. Stir bell pepper and tomato paste into onion.
Rub chicken with paprika and about ½ teaspoon each salt and pepper; place on vegetables, with thickest part of breast facing edge of dish. Cover and cook on high until chicken is opaque throughout, about 10 minutes. Remove chicken.
Remove garlic, slice off top, and squeeze cloves into a small bowl. Add mayonnaise and lemon juice; mash with a spoon. Stir into vegetables, then spoon onto plates and serve chicken on top.
Notes
If you are preparing this recipe as GLUTEN-FREE, just be sure to use a brand of mayonnaise that is known to be GF.