Preheat oven to 350°F (175°C).
Lightly grease an 8x8 or similar-sized baking dish.
Make the filling by combining strawberries, rhubarb, lemon juice, sugar, and cornstarch in a large bowl.
Toss until well coated.
Pour the filling into the prepared baking dish and spread evenly.
Prepare the crisp topping by mixing oats, almond flour, brown sugar, cinnamon, and salt in another bowl.
Stir in melted butter until the mixture is fully coated and crumbly.
Reserve ½ cup of the crisp topping and set it aside.
Sprinkle the remaining topping evenly over the fruit filling.
Bake for 30 minutes.
Remove from oven and sprinkle the reserved ½ cup topping over the partially baked crisp.
Return to the oven for another 15–20 minutes, or until the fruit is bubbling and the top is golden and crisp.
Turn the oven to broil on low for 1–2 minutes at the end to toast the top. Watch carefully to avoid burning.
Let the crisp cool for at least 30 minutes before serving to allow the juices to set.
Serve warm with vanilla ice cream or whipped cream. Enjoy!